It’s not always easy to pinpoint the source of one’s ADHD. It can happen after brain injury and I’m sure it can skip generations genetically. Exposure to cigarette smoke and/or chemicals can also trigger ADHD (say some studies). And, just because your mom is sensible and your dad was a successful engineer doesn’t mean that couldn’t have ADHD.
ADDitude Community Moderator, Parenting ADHD Coach & Author, Mom to teen w/ ADHD, LDs, and autism