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DEAR ABBY: My wife and I divorced after she had a year-long affair with a co-worker, whom she eventually married. Early in our marriage I suspected she was having an affair with a relative, which she finally admitted to after our divorce.

Now that our youngest son, "Douglas," has become an adult, he is beginning to strongly resemble his "Uncle Joel." I don't know if other members of our large family have noticed, but when I asked my ex if it's possible that Douglas is not my biological son, she became very quiet. I passed a note to Joel, but he blew it off without comment.

Douglas will soon be moving far away to begin his career and does not suspect anything. Should he be told who his real father is? Should his siblings be told the truth, or should I let Joel and my ex continue to lie as though nothing ever happened? -- DAD WITH A DILEMMA IN MICHIGAN

DEAR DAD: Unless you are 100 percent certain that Douglas is not your child, you should not tell him otherwise. And the same goes for his siblings.

Before you take this any further, my advice is to discuss this with your lawyer because children born "within the bonds of wedlock" are presumed to be the husband's. However, if there is irrefutable proof that you are not Douglas' biological father, he should be informed so he can be aware of any medical information he may need in the future.

DEAR ABBY: My husband and I are childless. I have two young nephews whom I adore. We have offered to baby-sit whenever my brother and sister-in-law need a night out. Sadly, we have been overlooked. Instead, our sister-in-law asks her younger sister to baby-sit. I understand that my sister-in-law is very close to her sister, but I can't help feeling insulted and a little jealous.

I'm a teacher, and my husband and I have good judgment. We also live closer than her sister does. I am struggling with these feelings, and I'm not sure if I should say anything. -- NOT FIRST CHOICE IN NEW JERSEY

DEAR NOT FIRST CHOICE: Of course you should speak up. It's certainly better than fuming and harboring hurt feelings. Not knowing your sister-in-law, it's hard to say why she has been reluctant to have you baby-sit. Perhaps she has simply fallen into a routine with her sister. Better to get this out in the open than to brood.

DEAR ABBY: A close relative became engaged last year. "Albert" is in his late 30s and has never been married. The family was delighted and welcomed his fiancee, "Claudia," with open arms. They have set a wedding date for later this year.

However, we have begun to witness Claudia's out-of-control behavior. There have been instances of screaming, abusive language and tantrums over simple things when she didn't get her way. She has always demanded that Albert support her behavior no matter how inappropriate it was.

Several family members had private conversations with Albert to warn him that the abuse will only get worse if they marry. Instead of heeding our warnings, he told Claudia about it. Now they are both alienated from the family and still planning to be married. What do we do now? -- AFRAID FOR HIS FUTURE IN ALABAMA

DEAR AFRAID FOR HIS FUTURE: Now you wait to see if you are on the guest list. And if you are, you will have to decide if you want to attend, which will imply that you approve of a union you think will be a disaster.

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