Contacted via Facebook recently and informed we had child after affair many years ago , child now 32 . Woman put other name on birth certificate , was married twice and told child different stories . No order of child support , paternity not established , woman said she does not want money just relationship with son . I live in California was never made aware , child is grown now what?

No order of child support

You have no child support to worry about. Your other concern would be what could happen if you die without a will, and he is proven to be your son.

I don't think it's crass to politely ask for a DNA test, of course. After that, why not get to know him?

At 32, you wouldn't have to pay any kind of support anyway.

So do you want a relationship with this person or not? That's all on you to decide now.

Yep lot of what if , I'm 60 and have kids of my own . I will contact and work through issues , just looking first at liability which I never planned for and why now

There is no liability. You probably have a will? Another father is on the birth certificate. Ask to see that when you ask for a DNA test (about $175). He is legally and officially the father regardless of the results of the DNA test, unless steps are taken to change that by all parties.
Wondering why now? Maybe his mother is feeling her mortality. I first wondered why she contacted you instead of a 32 year old adult son, but I suppose it makes sense since she knew you and he never did.

joypulv makes a very good point about your will. Be aware that if you don't have one (i.e you die intestate) that in most states if this person can establish your paternity then he will share in your estate along with your wife and other children. Assuming that's not what you want to have happen - make sure that you (a) have a will drawn up and (b) explicitly name your heirs in it.

NY goes a step farther - you cannot omit an heir. You must make a specific mention of that person and state that that person is entitled to nothing.

The old "for reasons he/she knows" language is no longer used because it was set aside after a Court battle over who knew what.