I wouldn't answer any questions unless you felt comfortable answering them. I don't always respond to every checkbox on a doctor office form myself, and sometimes a simple "yes" or "no" box doesn't help even if I did want to answer (it's not always a simple answer for some questions).

One thing I learned, though, may shed some light on why doctors are asking about these experiences:

I've been reading a lot lately about trauma and the development of chronic illness and even common conditions like type two diabetes and heart disease. It turns out more doctors are asking questions now about people's past abuse/trauma history to help screen for developing certain conditions and staying on top of them.

Some doctors might use their patients' answers to encourage people to seek therapy, antidepressants, etc because there is evidence that depression and trauma are linked to developing certain physical conditions, and try to prevent those from developing. For example, there's research that was published today online about how being treated for depression lowers the risk of heart disease.

Asking patients if they have a history of trauma/abuse came out of discussions and medical conferences based on a study conducted by Kaiser Permanente on 17,000 people, a study called the ACE study or Adverse Childhood Experience study (acestudy.org). If you look it up on Google, you'll find more info about it including people who formed support groups around it.