You are right that Muslims, like most people, tend to follow the religion of their parents, at least while they are young. And Islam offers a range of good teachings as well as harmful ones. Muslims have a wide variety of followers, just as other religions do, from wise, peaceful ones who are tolerant of others to intolerant, angry, and violent ones who harm other people.

It strikes me as a major oversight in the messages of their Prophet that those messages apparently neglected to explain how leadership of the religion should continue after the Prophet's death. That neglect resulted in the early split between Shia and Sunni factions of Islam, with violent consequences that continue many centuries later.