Horse breed been produced. Such restrictions have led to legal challenges in the United States, sometime based on state law and sometimes based on antitrust laws. Horses can crossbreed with other equine species to produce hybrids. These hybrid types are not breeds, but they resemble breeds in that crosses between certain horse breeds and other equine species produce characteristic offspring. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, the hinny, is a cross between a stallion and a jenny (female donkey). Most other hybrids involve the zebra (see Zebroid). With
Human male sexuality child they are raising is biologically theirs. Because of this difference, males have to adapt their own sexual strategies to accommodate the strategies of the females around them. Among other behaviors, this means that men are more likely to favour chastity in a woman, as this way a male can be more certain that her offspring are his own. Such a strategy is seen in males, and maternity is never doubted by the female, and so a chaste male is not highly valued by women. However, for men, female chastity confirms paternity, causing the male to compromise his sexual strategies