How much to diversify and when?

Notice: I have done no research for this post.

The concept of diversification is comon on the context of capital markets.  My friends and I often quip, "Good thing you have so many kids."  How much one should diversify and what determines the opimal amount of diversification is topic of which I am not familiar.  It came to my mind as I took a crap after 4 beers thinking that my girlfriend and I were unusually mobile because all of our friends are long distance.  We loose no camaraderie if we move, other than time zone effects.  Maybe this lowers our mean happiness wherever we are.  But, the freedom is great.

How many friends should one have?
Where should they be?

How many kids should one have?
With how many women?
In how many different places, in how many countries, of how many races?

Maybe I'll come back to this...I wish I was back in grad school.  I can only imagine the enjoyment of working with my committee of Tyler Cowen, Gordon Tullock, Roger Congleton, Ron Heiner, and James Sanford (Psych) on this.  Those were the good old days.