Genes? Anyone have a clue?

Question

Can someone describe to me about gene similarities in identical and fraternal twins and in siblings?

Answer 1

Identical twins share the exact same genome - they result from one fertilised egg splitting into two discrete units. Fraternal twins and other siblings have different genomes, as they are formed from two (or more) fertilised eggs, and each egg and sperm start with the same building blocks, "jumble" them up , then loose half. For this reson, siblings tend to only share half or so of their alleles...it's been a fair number of yers since I had to remember this stuff. :D