Genetic factors influence female infidelity and the number of sexual partners women have, British scientists said on Wednesday. They studied the responses of 1,600 pairs of identical and non-identical twins in a confidential survey to look at the impact of genes on behavior. "We found that around 40 percent of the influence on the number of sexual partners and infidelity were due to genetic factors," Professor Tim Spector, director of the Twin Research Unit at St Thomas' Hospital in London, told a news conference. But he added that environment and upbringing also play a part in explaining the variation in...