History Main / AllGenesAreCodominant

In a work with an InterspeciesRomance, the happy couple are very likely to pass on different alleles to the resulting child. This is normally where the laws of genetics are thrown out the window in favor of HollywoodGenetics. And in Hollywood, the three things that can happen are as follows:

* EitherOrOffspring: The child will be either parent's species with no hybridization.
* The OneHeroHoldTheWeaksauce route: The hybrid inherits [[HybridPower both species' strengths and none of the weaknesses]].
* All Genes Are Co-Dominant: The hybrid gets a half deal on ''all'' traits in a kinda-sorta-but-not-really incomplete dominance way. They have half of everything -- from physical appearance, to strengths, to weaknesses. This is probably an attempt at a more realistic aversion of the route above; but if one of the races has a severe imbalance of power compared with the other, it can have a similar effect overall.

PatchworkKids is a subtrope. Contrast RandomSpeciesOffspring when the offspring is biologically not like the parents at all.

* Cross a black chicken with a white chicken, and (once the babies grow feathers) you can get mottled black-and-white chickens!
** ''Depending'' on which kind of black, and ditto white, you are working on. Different types of black/white hybrids could be '''1)''' Black; '''2)''' White; '''3)''' "Blue" (which is [[NonIndicativeName actually grey]]); '''4)''' Mottled black and white; '''5)''' Barred, brown, pencilled, whatever, showing little resemblance to either parent colour.
*** By mottled, do you mean Splash? Splash is irregular patches of black, grey, and (few) white feathers. Mottled is an entirely different gene which makes each feather solid with a different colored tip. Not to mention dominant and recessive forms of white, or homozygous/heterozygous versions thereof. White isn't usually involved in the BBS (Black Blue Splash) continuum. [[DistractedByTheShiny But yes, there are lots of codominant genes in chickens.]]

** According to feline genetics Hollyleaf should have been a tortie. There's much more, but in general cat genetics are a lot more complicated than the Erins know about. They even admit they don't know a thing about cat coat genetics.

* In ''Literature/WarriorCats'':

%%** There are multiple male tortoiseshells in ''Warriors'', which are incredibly rare (about a one in three thousand chance). At least one of them, Redtail, is also a father, despite almost all male tortoiseshells being sterile.

** Even less realistic is Jon Kent, the son of the Pre-New 52 Superman who was introduced during the events of ''ComicBook/DCRebirth''. Jon seems to have his powers like flight and heat vision almost to the same level as his dad. The rub comes in that Jon's powers are unpredictable and sporadic. At first he'll be invulnerable but then a tumble from a tree will give him a concussion. It seems that as he grows his genes are fighting and shifting in order to find a more stabilized state. They ''do'' finally stabilize after the ''Black Dawn'' arc, giving him an overall power level that is comparable to, but still weaker than, Superman himself, but his overall potential is a case of HybridPower, with Batman claiming that Jon's full powers will surpass his father's and potentially grant him abilities that his father may never manifest. His unique genome ''does'' leave him deficient in other areas, particularly [[spoiler:his control over his Solar Flares, which can potentially kill him.]]

* In ''Series/StarTrekTheNextGeneration,'' Deanna Troi has a (telepathic) Betazoid mother and a (non-telepathic) human father, and is herself empathic: she can sense emotions psychically but not read individual thoughts ([[DependingOnTheWriter usually]]).

* {{Dhampyr}}s in ''LightNovel/{{Durarara}}'' appear to work this way, if [[spoiler:Ruri Hijiribe]] is anything to go by. Being quarter-vampire, they have more common vampiric traits and weaknesses in a diluted form (for example, they hate direct sunlight and garlic, possesses a moderate level of SuperStrength, [[HealingFactor heals noticeably faster than normal]], and has a thing for rare meat with a high iron content).

** Though a mixed race couple can have children who is closer to one parent more than another in this regard. Most people have some combination of "dark" and "light" alleles among the many genes that control skin colour, and only half of each person's genome is passed to any given child. If, say, both parents happen to pass mostly the darker alleles to a child, the child could end up considerably darker than the average of the parents.

Contrast RandomSpeciesOffspring when the offspring is biologically not like the parents at all.

** Played with in one episode of ''Next Generation'', where Worf finds himself on a planet where Klingons and Romulans were forced to coexist for mutual protection. He grows quite fond of a woman who looks like any other Klingon...until he brushes her hair back and sees her ears are pointed, outing her as half-Romulan.

* This happens in a nonmagical way in the ''VideoGame/WorldNeverland'' series. Children have a random combination of their parents' traits, so DarkSkinnedBlonde and DarkSkinnedRedhead characters are common.

* {{Dhampyr}}s in ''LightNovel/{{Durarara}}'' appear to work this way, if [[spoiler:Ruri Hijiribe]] is anything to go by. Being quarter-vampire, [[spoiler:she]] has more common vampiric traits and weaknesses in a diluted form (for example, [[spoiler:she]] hates direct sunlight and garlic, possesses a moderate level of SuperStrength, [[HealingFactor heals noticeably faster than normal]], and has a thing for rare meat with a high iron content).

** There are other half-demons in the series who look more like one parent than the other. Jinenji's demonic heritage is unspecified, but he is over ten feet tall and has a bestial face, while Shiori the half-bat-demon looks almost completely human (aside from her white hair, purple eyes, and dark skin for a Japanese child who spends most of her daylight hours indoors), and almost nothing like her demonic grandfather whose powers and duties she inherited. This is complicated somewhat by the fact that some full demons have a human form and an animal form that they can magically switch between, and it's unclear if the vastly dissimilar phenotypes are influenced by inheritable differences. It's explained that how a hybrid appears is really luck of the draw. Jinenji's father was a bishonen if you've ever seen one, yet their kid is more ugly than a [[Franchise/StarWars Hutt]] with his face caved in. Some come out to be beautiful and humanlike, others come out horrifying.

* Kryptonian/Human hybrids Follow this trope perfectly in any alt universe or future story that shows Franchise/{{Superman}} with children. Superman's children with Lois have his powers and weaknesses at half strength. Their children (when they breed with humans) are 1/4th strength and so on. In one Elseworlds, Superman's ancestor landed during the American Revolution, crushing it and creating his own British empire. The story is set in the present where Kal-El's genetics are so watered down, that he has no powers at all and his father was only marginally superhuman.

** There are other half-demons in the series who look more like one parent than the other. Jinenji's demonic heritage is unspecified, but he is over ten feet tall and has a bestial face, while Shiori the half-bat-demon looks almost completely human (aside from her white hair, purple eyes, and dark skin for a Japanese child who spends most of her daylight hours indoors), and almost nothing like her demonic grandfather whose powers and duties she inherited. This is complicated somewhat by the fact that some full demons have a human form and an animal form that they can magically switch between, and it's unclear if the vastly dissimilar phenotypes are influenced by inheritable differences.
** It's explained that how a hybrid appears is really luck of the draw. Jinenji's father was a bishonen if you've ever seen one, yet their kid is more ugly than a [[Franchise/StarWars Hutt]] with his face caved in. Some come out to be beautiful and humanlike, others come out horrifying.

** And that's disregarding the [[http://www.rawbw.com/~svw/superman.html mechanical difficulties]] inherent in human-Kryptonian intercourse.
*** That article disregards the fact that Kryptonian involuntary reflexes do NOT seem to be as strong as their voluntary movements, as neither Superman's blinks nor heartbeats nor digestive peristalsis seem to cause massive destruction of the surrounding terrain.

** Tedd. Father is Caucasian and has natural [[YouGottaHaveBlueHair blue hair]]. Nanase, Tedd's cousin on his mother's side, is a redhead of Asian descent and it's often extrapolated that Tedd's mother is too. Result: Tedd has purple hair and his eyes are slightly slanted (less than Nanase's). Nanase's recent magic-burnout turned her hair black, so it could be that having magics screws around with your hair-color.

A MixedAncestry trope.

** The combination of the power of the two species makes it so that it would be dangerous for any wyvern (or anyone with MixedAncestry) to have children themselves, but they are not actually sterile.

** Mules as well, although they are also a bit MarySue-ish (sterility aside), being described as "more patient, sure-footed, hardy and long-lived than horses, and they are considered less obstinate, faster, and more intelligent than donkeys."

* In ''Literature/HarryPotter'', this appears to be Creator/JKRowling's approach with the half-giant Hagrid. Normal giants are 20-25 feet tall, with extremely large bodies, and are not as intelligent as wizards. Hagrid is "Twice as tall as a normal man, and five times as wide," and [[BoisterousBruiser somewhat]] [[DumbIsGood bumbling]]. On the other hand, the other half-giant in the series, Madame Olympe Maxime, is just as large as Hagrid but more intelligent and graceful, and better at magic.

[[folder:Web Comics]]