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atomfullerene t1_iyw50yg wrote

Those are probably not recessive traits. In fact, they are probably influenced by multiple genes.

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Ein_The_Pup t1_iyvcev3 wrote

In order to inherit a recessive trait, an individual must receive two copies of the recessive gene, one from each parent. In the case where only one parent has a recessive gene, there is a 50% chance that the individual will inherit the gene from that parent and therefore have the trait. This is because each parent contributes one gene to each offspring during reproduction, and whether or not the individual inherits a particular gene is determined randomly.

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Rodeo_Pup OP t1_iywas47 wrote

So only one parent has to have a recessive gene and the other has a dominant one there’s actually just 50/50 chance and not a better chance you’ll inherit the dominant one?

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Ein_The_Pup t1_iywbeqx wrote

Not every gene is dom/rec. You don’t get one or the other. If one parent has a recessive, the other may have a recessive also. Therefore, it could be a 50/50 shot of you getting either or. Maybe your siblings all got one recessive and you got another.

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Srs_Bizz t1_iyx0w77 wrote

[Answering the original question, but not the specific scenario]

One way you can inherit a recessive trait that only one parent has is via the "sex chromosomes", particularly for individuals with only one copy of X. This is why XY individuals (traditionally, gendered male) are much more prone to certain genetic birth defects than XX individuals.

For genes carried on the X chromosome, if some of these genes are missing or damaged, a detrimental mutation (such as color blindness) will be expressed in XY individuals with a higher probability than in XX individuals because XY individuals only have one X chromosome. Basically, they don't have a counterpart gene on the Y that the body can rely on in place of the corrupted code on the X.

(second paragraph adapted from Wiki entry for clarity of explanation: https://en.wikipedia.org/wiki/Sex_chromosome#Medical_applications )

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