Children raised in space should be able to return to Earth as long as a rigid exercise program is developed. Because we normally live under the pull of gravity, our legs are important appendages, supporting our body weight, and our heart is an important organ, pumping blood up through the body. In the weightlessness of space, however, the muscles and bones of our legs and our heart muscles weaken, so astronauts must do a lot of special physical exercises to keep them strong.
Now if a baby were born in space, I'm not sure what kind of exercise could be devised to ensure that its heart and legs grew strong enough to endure Earth's gravity. That is a more difficult proposition.
NASA has some information on 'Living in Space'; I have provided their URL below.
Physical exercise builds strong muscles and bones. Even in conditions of abundant calcium intake, the bones will not be thicken and strengthen, if are not done regular exercise of carrying loads and walking.
In order to keep their minerals, the bones must be pressed, pushed and twisted against gravity.
The role of this gravity factor was demonstrated, very clearly, once the man came out into space. Although cosmonauts have had conscientiously their physical exercises, all the time spent in space, they have returned it on the Earth with surprisingly osteoporotic changes in their bones.
Although almost all types of aerobic exercises are beneficial to the body, what the bones actually need is a shaken ride, of at least 30 minutes every day.
This question is a little difficult as nobody has ever been to another planet. Mars is the next planet along from ours (remembering the rhyme; My Very Excellent Maid...) and it would take 60 years to get there. Even if you send a newborn baby, they would be 60 years old by the time they get there. Therefore they wouldn't be able to return to earth because they'd be 120 when they got back or dead. Very rarely people even live to 100! So, I wouldn't think that children raised in space would be able to return to earth.