Eli5: What are recessive genes? Why do we always get passed down genes that don’t show?
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FYI I’m a curious/nosey reader not an expert:
Recessive genes typically, almost always require that they are received from both parents in order for the trait they carry to show. Let’s use eye color for an example: you get a big B, from mom for brown, and a little b, from dad for blue. The big B is dominant over the little b so you get brown eyes but….you still get both genes from both parents. This means you are heterozygous for brow eyes(Bb). Homozygous would be BB (Brown eyes) or bb (blue eyes). Heterozygous can be Bb or bB. Gametes (egg and sperm) from parents are randomized disco combinations, literally life’s box of chocolates. So If you are heterosexual and you also meet a brown eyed partner that it heterozygous (Bb) for eye color there is a 1 in 4 chance you can have a child with blue eyes. We carry many recessive genes and lots of “junk” dna. If the coding poses no threat then why not pass it on a reduce enenergy on trying to weed it out? On the other hand our knowledge of genetics is always growing and genetics are always changing so we don’t fully understand the purpose of non-expressed dna and this is just a simple example; there can be other genes that override gene expression of certain traits. Life is a lovely misunderstood puzzle.
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