Dip difficulty is inversely related to body mass (mass of one's ass as my clients joke), more specifically body fat, and to upper body strength.
One of my female clients was still able to dip bodyweight + 25 lbs parallel for 8 reps, 5 months pregnant. Was able to get bodyweight at 7 1/2 months pregnant for 3 x 8.
I have other females that can get 8 - 10 reps with 45 lbs around their waist, but are generally around 15% bodyfat and well trained. Not BBs, but in shape.
I've found that it takes several months to a year to get to bodyweight for 8 reps depending on body mass and ability to develop upper body strength.
It can be done. Work at it, don't dip below parallel and control the movement (i.e., don't bounce at the bottom) unless you want shoulder and elbow problems.
Any female that is around or less than 20% bodyfat and trains consistently should be able to get at least 8 - 10 reps with bodyweight in a reasonable amount of time even if she is previously untrained.
W6