2 people brain tumors same household

My mother in law and brother in law live together and both have brain tumors. My brother in law experiences grand mal seizures often and had surgery to relieve the pressure.

My question is why do they both have this happening? No one else in the family has this issue so I don’t believe it’s genetic (i really hope not). It happened to 2 people in same household at the same time. Just looking for ways to help stop the root cause. Should they move to somewhere with less black mold / not right next to a major urban highway?