Variation is one outcome of sexual reproduction. Not only does recombination usually disrupt linkage disequilibrium in a population over time, but the law of segregation means that siblings will often receive different alleles from the same parent.1
As an illustration, click here. Sometimes nature just puts all its eggs in one basket….
1 – If the parent is homozygous, that is, carries two copies of the same allele, then obviously this isn’t so.
Posted by razib at 11:49 PM