polymathpoolplayer wrote:
...typical "baby in the family" pampering or relaxation of rules by parents, which tends to occur at the fifth or sixth child...
Well, my parents were certainly much more tolerant of my "eccentricites" than either of my much older siblings' (as they frequently remind me, even to this day), although I was only the third child--hence my "Baby in the family" response.
polymathpoolplayer wrote:
The conclusion I am seeing here is that it would be nice if polls on WP could allow you to vote in more than one box, to avoid a choice having to be too narrow, such as: "3rd and last child with adopted sibling whose age is between my age and my next older natural sibling's age".
No offense intended, but your poll offers too many options, not too few. You may also fall victim to the "sample with the built-in bias" as a result of your option sequence as well.
Furthermore, if you want to gauge autism likelihood versus birth order, then you must of necessity reject anyone who claims to be an only child--you'll get no useful data from those individuals. Note that some only children may select "Oldest child" simply because it appears first in the list of choices.
Please read
How to Lie with Statistics by Darrell Huff for a fun introduction to the pitfalls inherent in polling, as well as ways that statistics can be misleading (often unintentionally).