Is your sister's tree the same cultivar? If so, (and even if it isn't), you should ask here how she cares for her tree first.

There are so many variables that can affect how a tree grows...soil type, amount of water it gets, micro climate, fertilizer use or non use, proximity to structures, etc. etc.

I planted ten rooted cuttings, all from the same mother tree, in my yard this winter. The variation in their individual growth rates is astounding. Some are well over three feet tall and have figs on them all ready. The smallest is only about 5 inches tall, and the others are at various stages in between.

I'm sure some of the more experienced figgies will weigh in on this one...

Your best bet is to root a cuttingfrom your sister,and then you will have a fig just like her.
In your zone 10 seeds are usually fertille and will grow in new trees that are eather inedible male caprifigs,or female,cauducous,that needs polination,by the fig wasp,in order to be persistant ,hold fruits on tree till ripe.
Polination is done artificially,by placing branches containing polen filled fruit ,hanging in the female tree,at the exact rite time.

I agree with herman, sambyca you probably have a male caprifig.

I have 8 fig trees in pots, two have figs with this problem. One is a brown turkey and the other is italian everlasting.. The fruit turned dark blue and looks dehydrated. There is no flavor and they are kind of sticky. The other 6 trees are great and the figs are delicous. I've had all the trees for over 4 years and have never experienced this. Any ideas???