Q: My 10-year-old daughter recently told me her 11-year-old stepbrother tried to kiss her inappropriately the other night before he went to bed. They share a room, and she was already asleep. He admitted to it, but is very embarrassed, and my daughter is horrified. We aren’t sure what to do at this point. My husband and I have only been married six months and his son goes back and forth between his mother’s home and ours. What do you suggest? What’s good ex-etiquette?

A: RED FLAG! What were you thinking? Unrelated children of the opposite sex should NOT share rooms — and that you would even consider this with two children in the midst of puberty suggests that Dad and you have been preoccupied with your own relationship and have not considered appropriate living conditions for your combined family.

People often change in their bedrooms, and retire to the room and close the door for privacy — both are inappropriate behaviors for two unrelated children of the opposite sex, particularly the age of your children.

Good ex-etiquette would have been to find a home more appropriate for your combined family before moving in together. Ex-etiquette rule No. 1 — “Put your children first!” (Even if you can’t move in together or get married when you want to.)

Parents often see their children as innocent little ones and don’t realize that at 10 or 11 their bodies begin to change and they start to have sexual feelings. Plus, many school districts initiate sex education at the fifth or sixth grade level, not to mention what kids are exposed to in movies or television!

This does not mean that all will experiment, but it also doesn’t guarantee that they won’t, and they need clear family rules and boundaries to guide them. It doesn’t sound like this was offered to them if you expected them to share a room.

Something important to consider: How children respond to each other has a lot to do with when they initially meet. For example, there may not be as much concern about leaving a 16-year-old boy alone with his 15-year-old stepsister if they have been raised together since they were 4 and 5, as there would be leaving alone a 16-year-old boy and his 15-year-old stepsister whose parents have only been together for six months. But, for both examples, the kids must understand the consequences if the house rules are broken, and parents should not set the kids up for failure by ignoring potential problems, and should put in checks and balances to keep them from making mistakes.

Finally, after you move the kids into separate rooms, seek family counseling. Adolescents, in particular, have difficulty coping with humiliation and embarrassment, and may need the help of a professional. Your family needs to sit down together and address what has happened. Since your stepson lives in two homes, his mother should also be kept in the loop. If a change in the sleeping situation is impossible for now, a temporary change in your parenting plan may be in order.

Dr. Jann Blackstone is the author of “Ex-etiquette for Parents: Good Behavior After Divorce or Separation,” and the founder of Bonus Families, www.bonusfamilies.com. Reach her at:

drjannblackstonegmail.com