What age to start become a parent(s)?

As
Mine I don't have children right now. I'm sure those that I wanted to have children (2 or 3 kids), and getting a job or work hard to stay at home mommy. My mother had been 3 times pregnant at her age 17, 19 and 20 years old and my father is 1 year older than her, on his age 18, 20 and 21. Plus - he was last one for his wife (my stepmom) for nearly 20 years marriage; he's 29 and she's 24 - 5 years apart! My stepmom got her second pregnant, is same way that year, my youngest half-brother is now he is 18. Holy moly! That is longtime marriage and as well - my father got married her in July 1998, and I went to see her at Exeter Hospital to hold my baby half-brother in Oct. '98. 
Tell me about ask your questions, if you don't know what their age (like adopted), and can think guess your parents' age or your age at birth, if your partner age to have a plan parenthood, and at last - so how many children do you have?