Does OCD occurs from childhood? Notice!

My brother has been recently diagnosed with OCD... He is getting reptitive thoughts unnecessarily.he feels pressurerized on his own and it leads to stress eventhough he is taking Serotonin tablets. My main notice regarding him is  since childhood days..he traumatized with some incidents and actions He got tensed and feared for some unnecessary things.. 1)Does it impact those childhood thoughts and actions severe lead to OCD in his adulthood? And also he is influenced some bitter experience in childhood due to family environment & some social causes 2) is this also one of the factor OCD occurs in the adulthood..in our family ni history of OCD.but his past history in childhood was unexpected things...Does those emotions and family environment cause OCD in adulthood? 3) my fear for him is,IS this OCD leads to stress and severe compulsions in future even taking medications? How to get rid off his past history and how to recover his condition from OCD?please clarify sir/madam..