Hi Elvis, I don't own Jack either, but do own yorkshire terriers, and think all small dogs get a bit of bad press. If you are going to a rescue center, the dog should have been assesed, and you will be able to talk through any worries that you have with them. When bringing any dog home, whether it be a rescue, a puppy etc, rules need to be applied when there are children involved, talk to your kids about the responsibility of owning a dog, explain that the dog may be shy, stressed etc and will need time on it's own etc [time to rest, time to play]. Any dog has the ability to be aggressive, and with some awful exceptions there is some amount of provacation when a dog bites.....my three yorkies are fine, but my boy Harry hates to be picked up, I explain this to any children that come into the house... When I one day I found him barking and growling at a friends son, she went mental at me! She phoned and apologised later after her son had admitted to picking him up.....enough said!!!
Hope this helps
Lisa x