A mathematical model of a population genetics: Effects of genetic variation on homosexuality

This study deals with simple mathematical models for the purpose of generating testable prediction in genetics. The genetic effects in human population are because of the following four factors, (i) paternal, (ii) maternal, (iii) environmental and (iv) idiopathic. For the measurement of genetic characteristics, the environment also plays an important role. In the present paper we analyze this linkage for homosexuality for the first three factors because the fourth one affects a very little population. This study provides genetics and evolutionary basis for making generating testable predictions specifically where the environmental factors affect the characteristics of genes which also influence homosexuality. The effect of environment on homosexuality is highlighted because earlier studies confined only up to the paternal and maternal linkages. We consider two types of selections (i) direct selection with environmental effects (ii) combined selection with direct, maternal and environmental effects. The objective of this investigation is to provide the conditions for the maintenance of genetic variation of genotype of male and female. We concentrate on highlighting homosexuality as a result of variation in genes. Numerical results are obtained by taking illustration. The sensitivity analysis is carried out to explore homosexuality in terms of fitness loss and fitness gain.