I don’t know about 4 and 5 year olds but I think 11 is well before puberty and I sure as hell had sexual feelings by 10 or 11. There was a whole lot i didn’t understand but there’s a direct line from then until now regarding emotional content and fascinations and imagination-content from masturbating then through masturbating now.
It’s different for different kids I guess.
I didn’t have a lot of crushes as a kid, just a handful that I remember. Always boys my own age. For me, they were sexual (in a way that didn’t involve wanting to HAVE sex or be intimate beyond holding hands and pecking - hell, I didn’t want to have sex until I was 18).
I can’t remember a time when I didn’t have sexual feelings and get aroused. My sexual desires changed a hell of a lot around 13-14 (I didn’t finish puberty until around 16 - at that same time I started being attracted to men who looked adult) and even more as an adult when I started actually being intimate with people, but the feeling of crushing on someone is always the same.
My boyfriend’s first childhood crush (when he was like 4) was Chastity Bono. His family have never stopped making fun of him. 30 years later he ended up with me; he’s still into blonds with overbites.
When I was in my 20’s an 8-year old girl in my neighborhood had a cute little crush on me.
She called me when she was 18 and we dated for a while.
Okay, I thought that was adorable until I read the second paragraph.
Then I thought, “Creepy…”
When I was 4 I had a crush on Greg, the yellow Wiggle. I hadn’t thought about it until reading this thread, but he was totally my type - fifteen years later, I’m still very attracted to dark hair, dark eyes and a cute smile, and musical talent is also a definite plus. But I wouldn’t describe my crush as sexual. I wanted to watch him a lot, and played imaginary games where we met and he liked me too, but that was it.
Looking back, I know that I did experience arousal as a young child, and as even sven says, it was related to stuff that’s since become a kink of mine. I didn’t start associating the sexual feelings with people I had crushes on until I was about 14, though.
My uncle and aunt, married for 30 years, started their relationship this way. He told her, “Call me when your 18, kid” and forgot about it. When he was 31 or 32, she called him up upon turning 18.
Can’t make this stuff up!
I saw a couple on tv years ago that had the same situation. Was your uncle a boxer by any chance?
Tina Turner singing “I’m Ripe” ring any bells?
Seriously, my first little “crush” was in kindergarten on a chick named Jessica. Never went anywhere. Microdick and all. But my two longest (in duration) relationships have been with women named Jessica. My current academic advisor’s name is Jessie and a friend whom I’d bone if drunk enough is also of the same name. I think it’s bizarre.
I had my first sexual fantasy at age 5, and it was accompanied by a “funny feeling” in my genitals. Obviously I didn’t know it was sexual for many years, but it definitely was. Interestingly, the kid who was the object of this fantasy happened to be of a type that I’m still attracted to. So it appears that our sexual taste is established very early.
I was in love with Matthew Broderick as a kid (especially from Project X and War Games). I wanted to marry him, and I had dreams about him, but I don’t actually think it was sexual.
The crush I had on Travis in my class definitely was sexual, though it that little kid way where you have very little idea what sex actually is, beyond kissing in the nude.
+1 for this, down to a ‘t’. 
edit: I may have been a TAD older, maybe 10, but still no sexual component. I had ‘crushes’ on Wilder, and Anthony Hopkins (!) and The Greatest American Hero without thinking anything about it other than I wanted to wear them like blankets and snuggle. (No, trust me, it wasn’t a daddy thing, either, lol)
So maybe we’ve a built-in attraction to what we will want to get with when we’re older; it’s not like sex has ever had a whole lot to do with the developed brain or anything. 
Hrm, thought of something. My first real, long, stupid-in-awe real life crush was my friend’s brother. The attraction was INSTANT, and incomprehensible, and I was 8 and he was 16. We met for maybe 2 minutes at a school cake-walk. Flash forward a few years, during which this friend and I didn’t run into each other. We caught up in high school, I met her brother again…SAME DAMN THING. Hadn’t thought about him at all during that time, but apparantly that shot-through-the-heart feeling is only loosely tied to sexual hormones. (Carried that torch for the next ten years, damnit!)
Or we’re all a LOT hormonal than we think at a MUCH younger age than we suspect. 
Had another flashpoint experience like that with someone I met at church camp. I was 9, he was at least 15 <which was a huge gulf at the time, of course>. Despite this, we both just kind of stared at each other, he asked if we’d met before, I said no, we stared some more, shook our heads and went on our merry 9 and 15 year old ways, respectively.
I know all that is supposed to be hormones but good gods, they’re not very convenient, are they? Why couldn’t I have had those hormones flowing over my best male friend of 15 years? WHY?!?!
Mother nature is a bitch, I am convinced.