What is the stance of Islam on the original sin?

The lesson that Allah taught mankind, on accepting Adam's repentance for eating from the forbidden tree, represents the first incident of the Lord's forgiveness to mankind. The Christians' belief of inherited sin from Adam is meaningless, as no bearer of burden will bear the burden of another. In other words, everyone will be alone responsible for his own sins, and this is a manifestation of the Lord's mercy. Man is born pure and sinless and becomes responsible for his deeds since the age of puberty.