Definition: Precombination is a process in which two or more genes are combined with each other to form new combinations. This can occur through the exchange of genetic material from one gene with another gene, or it can also be due to the addition of alternate alleles to a dominant allele.
Examples of precombined genetic material include:
1. A gene that carries an X chromosome and a Y chromosome in a diploid cell.
2. A gene that carries two copies of a particular gene on its own (e.g
precombination