The tendency of certain alleles to be inherited together is called

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.

sex cells are usually half's then they find another half and make a fertilize egg

if you know your abc's you should be able to get your answer or just use google