Wrong date of birth in many registrations lately

We are noticing that the date of birth field for registrations is often, lately, coming back with the date the person registers for an event instead of their actual date of birth. The default for selecting a date in a form field opens a calendar and defaults to the current date I believe (see image included here).

One person who registered recently swears he entered his date of birth and also gender and it came back with the wrong date and gender. hah!
I think in 99.9% or more of cases, no one registering would have a date of birth of the day they registered. Is there a way to improve the date selection form field to help prevent these issues?

Thanks.