What are reasons nurture is more influential on a personality then nature?

[Penny]

Your nature could be outgoing, but if you have abusive parents you can become very shy.
Nurture can change the way you feel about yourself, the world and others, nature is just a base.

[brittany]

What challenges solutions made by the "nature" side?

[John W]

As evidenced by monozygotic twin separation studies and studies of non-separated dizygotic twins, variation in personality traits is mediated to a significant degree by genetics. Obviously, children raised in an abusive familial environment will be at an increased risk of developing a number of psychological disorders, however in normal circumstances genes are the principal regulators of one's temperament and intelligence.