Becoming a LandlordYour house appreciating at 5% annually = $25K/year.Your parents' larger house = $30K/year.Financing the PlanTake out a mortgage on your house to buy your parents' house.If their mortgage rate is lower than today’s rates (6.75%), keep their mortgage and assume it.Why It WorksYour tenants pay the mortgage—not you.Each monthly payment includes ~$300 toward the principal.

Principal mortgage balance is $159,531.

Also, it's likely that a slightly smaller amount of each payment will go toward principal since the loan balance is higher and the rates are likely nearly the same once the MI of 0.5% is added to the rate.

Home mortgage is $3700/month and $500/month extra payment towards the principal.

Not having any other investors around is a drawback, but where do you live and have you even looked for real estate investing meetups closest to you?

If you are just looking for principal protection assets you can do a lot better than empty houses, if that's what you are doing. 

This is not the best way to invest in real estate as you lose out on principal pay down but it gets you instant income that you can make mostly passive by hiring out the property management.

@tom shallcross summarized this well in another post and just inflate your numbers up for a $665k purchase price and $2300/mo per unit for rent.Borrow 80% which is like $3700/mo for Principal, Interest, Taxes, and Insurance.

The drawbacks are the prepayment penalties, higher downpayment requirement for purchases, and higher rates in general. 

Principal paydown is now around $2k/monthTenants are great.