How old is too old to start a family?

My grandfather was 40 when my father was born in 1910.

My father was 48 when I was born in 1958.

I was 47 when my 5yo (pictured in my avatar from a couple years ago) was born in 2005.
My wife was 44.

New life is a good and sweet thing at any age.

I had no idea my parents were some twenty years older than most of my friend's parents
while I was growing up until I was an adult.
I'm probably more active with my younger kids than a lot of fathers in their thirties,
but even if I wasn't it wouldn't matter.

Fathers pass on the important stuff to their children through osmosis.
It's a mysterious thing. 
It's not what you do with your kids that matters most,
it's who you are.

My mom died when I was 26. (she was 42 when I was born)
My dad died three years later.

I don't feel cheated at all.
I still miss them, but I also continue a relationship with them through prayer.
Two of my kids lit candles for them at church yesterday as part of our family tradition.
My dad would have been 101 last week.
We had a party for him last year to celebrate his 100th birthday.
100 candles on the cake.
Nearly burned the place down.  

I had two wonderful parents, so what's to complain about.
By the time I was an adult, I always knew that they would die when I was still young,
so their deaths weren't a shock. 

Life is good.
Pass it on.  

Regarding the birth defect issue,
it's my opinion that no one should even have sex
unless they're ready to meet their responsibilities
and bring any life that may come from the act into the world.

I grew up with a cousin who had Down syndrome.
I have an adult niece with Down syndrome.
Conceiving Down syndrome children is possible for 
parents of any age.

Persons with Down syndrome are just like any other persons
except they tend in general to be nicer,
have a better sense of humor,
and are generally way more flexible.

Sadly in the United States,
roughly only 1 in 10 children who are conceived with Down syndrome
live long enough to be born.  

The biggest thing I think of is how old my kids should be when they have to worry about taking me to the nursing home, handling my home and personal business, and planning my funeral.  While those things could happen at any age, sure, I like to think positively and that this would happen after I turn 70.  So, I think I would like to be under 40 when I had kids - personally.   Not only will they be older and more established, but most importantly way more capable!

This is a big reason why I initially decided I probably wouldn't have kids.  I was 25 when I got married, but my husband was 43.  I felt like each year he got older, the harder it would be for a kid to have an older dad.    When little Jimmy was in high school, what would it be like to have a senior citizen as a parent?    It didn't feel right to me and I didn't want to have to decide right away.  As the years have worn on, I am very happy with that decision.