I don't want to always stay at her place since my kids are all teens now. 

If not, my experiences with designing for families is that once kids are teens they retreat to their bedrooms on their phones, and only come out for pizza, so don’t worry about a “family space that includes teens.”

gen Z covers a large range (young teens to mid 30s). 

A 12 x 15 bedroom can easily fit four kids in bunk beds or two teens/adults, whereas a 10 x 8 room would be really tight.

I was not taught anything about investing or tax strategy as a child/teen, only to save money and don't buy unnecessary things (which is an extremely slow way to build wealth). 

Their core product funds return low teens IRR.

If you get a loan to buy the real estate you would even get interest deductions, while the renters are paying down your debt making your IRR in mid teens.  

And like Chris notes, if you start getting added to a dozen syndicator lists, all of whom are buying large-scale, Class B, Value-Add Multifamily deals in the suburbs of major metros, and 2-3 are projecting 30% returns, 2-3 projecting 20% return, and the remainder are in the mid-teens, I would really dig hard as to what is going into those 20-30% projections.  

I was driving around there one time and got surrounded by a group of teens with stun guns laughing at me. 

I have a good income producing job, however, I have a 6 member household with teens, preteens, and children who are eating up my house like Pacman, lol.