I would definitely say it is NOT "a boy thing". My youngest, Liyah, could climb over 2 baby gates stacked on top of each other (6 ft) at 11wks of age. More than once she climbed out of an xpen at a show - caught instantly because she got out and ran straight to me to greet me (thankfully). If she couldn't get over a gate in the house, she would body slam it until it came down. Now on occasion she will still climb over a baby gate in the house (if it is past her bedtime and she wants to go upstairs to her crate).
The thing that always amazed me is that she only briefly tried to climb on the 5ft chain link fence outdoors - but never went up more than a couple feet. That said, would I ever dare leave her outside if I wasn't around - no. Because I do think if she were bored she would be over it in a heartbeat.
Liyah can open any door in the house that isn't locked (puts both paws around the door knob and turns the knob) - needless to say, our front door is locked at all times. She opens Brando's and Ruby's wire crates if she wants them out. Of my 3 she is definitely the most clever - and must be watched like a hawk! I will say that I mostly just chalk it up to the fact that she is still a youngster (16mos).
The only mischief Brando ever gets into if he isn't getting attention and wants some is to grab a piece of clothing and run thru the house or starts to chew on something he knows he shouldn't. He's an angel (as is Ruby) when compared to Liyah.
Having 2 girls and 1 boy in the house - my take is the boys are easier.
