Nfk I have seen a range of responses, from the constructive 'we love you, but hate what you did, and will support you as long as you deal with this' to 'get out of our lives, we never want to see you again as long as we live.' Families and supportive friends who understand what they did can be incredibly helpful, because they don't accept excuses and will alert police and probation officers if they become suspicious.
Unfortunately, these helpful families are few and far between, and tend to crumble under the strain. Most don't want to discuss it. It would be better for society if families and friends could find it in them to support and monitor sex offenders, and only socialise with children when the offender is not there, but this often ignores the needs of the victims of abuse.
Where abuse has happened within the family, knowing that dad, uncle or grandad is back in the bosom of the family is hurtful and squeezes them out of their source of support. Imagine an abused grandchild visiting grandma when abusive grandfather has gone out to allow them time together, and there are signs of his presence all over the house. Or, on mum's birthday, seeing the card from both grandparents on the mantelpiece, reminding the child he still has indirect contact even if they don't want it.
Social services will do sensitive family reintegration work, but it doesn't repair things or take away memories, and most sex offenders get rejected or have to live separately after attempting to fit back into the family.