BIL being weird

Hi mummies any one have brother in laws that live with you? Currently am living with my in laws and my BIL also. i noticed everytime when my MIL and only my MIL change my baby girl diapers HE WILL ALWAYS GO AND SEE. He also very into giving my daughter baths. shes already 17months and understands. as a women, i think is not right. it makes me uncomfortable and weirded out. Am i overthinking???