Is my house a multifamily house?

[Kevin Lee]

I've been living in this house for 20+ years and was just a baby when we moved here. My parents aren't sure if this was originally a multifamily house that the previous owner converted to a single family. How can I find out if my house is indeed a 2 family house? We are considering converting it into a 2 family if it's possible and potentially renting out one of the units. Thanks for your responses in advance!