The most important one, as @Tim Ryan points out, is the question of whether the investor is single or married.

Background:  Late 30s, married with two young kids (4 and 2). 

I used to be convinced that in order to get into the land development business you had to marry a developer's daughter or be born to a developer.

Are you looking to get an investment property at 20% down or a primary residence you can house hack (rent the rooms in the house you are living in), or a primary residence (better for people who are married/have kids/don't want roommates) where you live in it for 12 months then rent it when you buy your next property to repeat the process.

If you purchase a property for $100,000 with say $20,000 down; and 3 years later sell said property for $140,000 while the mortgage has been paid down from $80k to $70k, that’s a cash out of $70k, or a $50k gain that can be used to pay down debt.Of course the easiest answer is to marry someone with no debt instead. 

If he is still married, they can exclude $500K.None of this should have an effect on his social security or part time job.Good Investing...

He explained that back then, the options were simple: you either lived at home, got married, or lived in a house owned by someone else.

I am married with 2 kids and about to have a third soon.My sister lives in the KCMO area, specifically in Lees Summit.

I believe the exclusion limit is $250,000 for single individuals and $500,000 for married couples.

Simply own and live in the home for 24 months of the past 5 years from the date of sale, and receive a tax benefit of up to 250k of excludable capital gains from tax or 500k if married and filing jointly.