1. How old do the scorpion need to be before you can sex them?
2. when can they begin to breed?
3. Can you breed scorpions from the same batch of babies, or will this not turn out good?

Since this is in the emp section, I'm guessing that's the species you're wondering about.

You can sex them as soon as you can get a clear look at the shape of the genital operculum.

They can begin to breed when each one's telson is a dark brown (meaning it's mature, in the case of this species).

There's nothing wrong with breeding siblings.

1. depends on the species. I'm assuming your refering to emps since this is the emperor scorpion section of the forum. In which case all you need is to be able to count the pectines. Which is easier when they're aren't so small.
2. As adults. Again depending on the species as to how many molts make them adults. I can't seem to remember how many molts for emps but I believe it's seven(ish)
3. You can interbreed with no problems.

ha mike beat me to it.

Yes I was refering to emperors. Thank you both for yalls help. The reason I asked was because I am selling my babies and one buyer wanted a pair. Just needed some information so I could let him know. Thank yall again

i didn't know emp siblings could breed with no problems.
Awesome. so i can get a whole bunch of emps then!?

Assuming your whole brood lives to adulthood, yes.