Answer:
a) Competition over mates
b) Diet
c) Evolutionary history
Answer
A stem cell has both positive and negative ethic effect
Explanation
Some people think it is ethically wrong to change natural stem cell. According to such people stem cell should not be used for research or other purposes because it directly influences the life which is going to develop from a stem cell. Stem cell use has an ethically positive effect as it treats the number of inherited diseases and everyone has the right to get a child of gender which they want.