Close relatives resemble each other more than unrelated individuals on the average but not necessarily for any particular trait in particular individuals. Second, individuals may tend to choose each other as mates, not because of their degree of genetic relationship but because of their degree of resemblance to each other at some locus.
Variation allows some individuals within a population to adapt to the changing environment. Use the probability or forked line method to calculate the chance of any particular genotype arising from a genetic cross.
Ignoring seed color and considering only seed texture in the above dihybrid cross, we would expect that three-quarters of the F 2 generation offspring would be round and one-quarter would be wrinkled. Each parent passes an allele at random to their offspring resulting in a diploid organism.
In many organisms — including humans and fruit flies — the sex of an individual is determined by specific sex chromosomes, which scientists refer to as the X and Y chromosomes.
Genetic variation is advantageous because it enables some individuals and, therefore, a population, to survive despite a changing environment. Brothers and sisters do not all have the same eye color, and blue-eyed people are not all related to one another.
Sex and the Red Queen.
William Birky Jr, Timothy G. Sex and the Red Queen. In humans, there is a positive assortative mating bias for skin color and height, for example. Given that sexual reproduction is costly from an evolutionary point of view, one could wonder why not all animals and plants reproduce asexually.
If mating between relatives occurs more commonly than would occur by pure chance, then the population is inbreeding.