Marcy believes that the outcome of athletic contests depends so much on luck that it hardly pays to put any effort into her own athletic training. her belief most clearly illustrates what?

I believe the answer is: an external locus of control

People who believe in external locus of control will perceive that everything that happen in their life are outside of their control.

Because of this, such people tend to blame all of the failures in their life to 'luck' , deity, or other people's actions rather than focusing on putting the effort to maintain their success. On average, people with external locus of control tend to unable to get into leadership positions due to their sheer negativity.

answer; ///the above statement is (true); //

as university of miami psychologists debra lieberman and adam smith pointed out in a recent article in the journal current directions in psychological science, humans have social and psychological mechanisms to deter incest. with very few exceptions, marriages between brothers and sisters and between parents and their children are verboten in every human culture. the primary psychological anti-incest mechanism is the yuck response. even the idea of sex with their mom or dad, bro or sis is upsetting to most people. the psychologist jonathan haidt has found that nearly everyone is repelled by the prospect of brother-sister sex, even in hypothetical situations in which there is no chance of pregnancy).

the biological cost of incest

this raises an interesting question: just what’s so bad about incest? sure, having sex with your dad or your sister seems gross — but why? some anthropologists have argued that incest taboos are learned social conventions. this explanation, however, doesn’t make sense to me as it does not explain the widespread existence of anti-incest mechanisms in creatures ranging from cockroaches to chimpanzees. second, the incest taboo is about as close to a universal law as human moral rules get.

why should mechanisms to avoid incest be so widespread both in nature and across human societies? the answer is simple. the problem with having sex close with relatives is that there is an astonishingly high chance that your offspring will be born with a serious birth defect.