The Vale of Glamorgan council had known about the youth's past
A father whose children were sexually abused by a 19-year-old placed in their care has defended social services against what he calls a "witch hunt".
He said the family wanted to prevent a repeat, but that would not happen if people "bayed for the wrong blood".
Vale of Glamorgan council failed to tell the family about the teenager's past offences, and it is investigating.
The father urged people to wait for the results of the investigation and said sackings were "not always the answer".
The father made the comments in an e-mail to BBC Radio 5 Live's Victoria Derbyshire programme.
He said the couple could not undo what had happened to their children but could try to make sure it did not happen again.
"The only way to move forward is to find out what went wrong and to see if failings in procedure, common practice or lack of training are to blame," he wrote.
"What we ask is that however appalled you may be, sacking the boss, or anyone for that matter is not always the answer."
The teenager was given an indeterminate sentence of imprisonment at Cardiff Crown Court earlier in March after admitting raping and sexually abusing the couple's children.
The couple are awaiting the outcome of an "urgent case management inquiry" launched to discover how the teenager was housed with the family as part of the council's adult placement service.
The confirmation that social services knew of the teenager's background came earlier this month as the council issued an unreserved apology to the family and revealed that disciplinary action had taken place, but did not provide further details.
The father's statement in full:
I am the father of the family whose children were abused by the young person placed in our care.
Unfortunately, recent newspaper articles and our TV interview, although containing largely accurate detail, have focused on the events themselves. This was never our intention. Our intention was that we could help everyone to understand our wishes in how we can best move forward to prevent this from happening again.
It is my hope that someone out there will now print or broadcast this short statement in it's entirety to get the real point across.
As a family we have had two months to try and return to some semblance of normality. We can't undo what happened to our children, but what we can do, is to try to make sure that this never happens again.
This is not going to happen if the public continue a witch hunt against social services, and continue to bay for the wrong blood.
The only way to move forward is to find out what went wrong and to see if failings in procedure, common practice or lack of training are to blame. This is especially close to our own hearts. Our family has in the past been victim to a knee jerk reaction by an employer seeking a scapegoat following criticism.
We have had to deal with the deeply damaging consequences of that decision. We do not want any more innocent individuals or families to be made to suffer as a result of this case.
To this end, the public should be made aware that social services is a large and complex organisation, with many, many departments under one umbrella. In this particular case, we know that the Adult Placement Service has already had to endure targeted harassment.
It should be made clear that to our knowledge, the lack of information that lead to this young person being placed with us, originated in other social services departments, and not within the Adult Placement Service.
What we ask is that however appalled you may be, sacking the boss, or anyone for that matter is not always the answer. It may be that procedures require complete overhaul, or more robust training be put in place in order for already strained staff to do their jobs well and for the right information to be in the right place.
Please, please, please, just let this investigation take its course. We as the victims, have every confidence that it will be conducted thoroughly and without bias, and indeed it is already being independently followed by the NSPCC to ensure just that. Please trust, as we do, that the right people will be held to account and will be dealt with accordingly.
Lastly but by no means least, we want to thank the Vale of Glamorgan police, particularly the CID who dealt with our case. Their sincerely caring attitude was commendable, particularly with regard to their interaction with our children. We really can't thank them enough for helping us through a very difficult time.