What Causes Swollen Wrists?

Both of my wrists are swollen and has been that way for years. There has never been any pain, but that swelling appears to be generational with the women in my immediate family who are overweight. Again, it is not painful, but it is there. I am 64 years old and I noticed today that it is a swelling which remains slightly dented if pressed on any part of it. My ankles are not swollen, just the wrists.