That's a neat coincidence!
You both have Sun in Gemini.
Also, you are both likely to have your Sun in the 7th house.
Any other similarities are not able to be known by only the information you gave.
I'm not sure if you have made a chart before ....
If you want to make a chart, go to this site: http://www.spiritualforums.com/vb/re.../www.astro.com
Go to 'Chart drawing/Ascendent', and put your birthdate, time and place in the required spaces. Your chart will come up.
Where it says AC (left side of wheel) - the section from that line to the next, is the first house. (You will see a number 1 if you look at the middle of the wheel). The houses go along from there, till the 12th house which connects back to the AC point.
To the left of the wheel, in a box, you'll see all the symbols for the planets, and next to them, the name. (eg circle with a dot, is the Sun.)
Next to that, in blue, is the degree and sign each of those planets is in.
(each sign has 30degrees).
This way, you can check what sign each of your planets is in, and what house they are in.
And then, you could compare them to your mom's chart, if you want to see any other similarities you may have.