My impression is that genetic information in eggs and sperm are consistent per individual. If so, what causes the combination of those two sources to vary so greatly? Some brothers or sisters are total opposites of each other despite the same “ingredients”. How does that happen genetically? Why would only one of a couples children inherit an expressive genetic disease? Etc.
In: Biology
Parents, siblings and child share 50% of their DNA with you. Grandparents, aunts, uncles share 25% w/ you. First cousins share 12.5%. For each generation back and forward from you, your DNA is halved. You have 1.56% of your great-great-great grandparents’ DNA. The ELI5 is that the DNA from all your ancestors is shuffled and halved each generation. The halving is consistent, the shuffling is a free-for-all.
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