Assume that a father and son from the same jurisdiction both commit similar crimes (not necessarily together), both of which will land you in the same type of prison (minimum, maximum, whatever). Will the BoP try to put them in the same facility? Assume they both want to be in the same facility.
They don’t go out of their way to put relatives together but it happens. There’s no rule prohibiting it (at least not in New York).
I saw a documentary some years back about a father and son both convicted of child sexual abuse of some kind, both claimed innocence. They were put in the same facility, but separated, and weren’t supposed to be in contact, but the guards would let them stand near opposites sides of a fence to talk to each other outdoors.
I’ve dealt with some uncle-nephew, father-son, and brother combinations in the same prison at the same time. The administration position is either “we don’t care if they happen to end up in the same place, it’s not a security risk” or “we’ll keep them from being at the same facility at the same time due to security concerns”. The latter happens when it’s felt one person coerced the other into committing crimes, or other abuse/manipulation issues are involved in the relationship.
I don’t believe they would ever decide to go out of their way to put family together.
In the case of the UK, it depends.
They would need to be rated at the same level of security requirement - so if you had a fine defaulter who was rated for Category D, and a violent armed robber rated as Category A, B, or C then they would have no chance.
Other security considerations would be the likelihoods that they would work together as a team that presented risks of violence or security then that would not be allowed.
If they were on similar security levels, and perhaps even co-accused then there is a realistic prospect, and they can make out an application to be located in the same prison.
There is also the chance that they can apply for an inter-prison visit. This can be something of a pain to organise, but the main justification could be that there is a possible benefit to retaining family contacts - it would be closely scrutinised.
If they are both non-violent offenders then the chances improve, but if they are in for mid to high level drug dealing, probably not.
Alcatraz did. And they were told to keep them apart then let them cell next to each other.
That raises an interesting issue.
What happens when they are released on probation?
Is the felon can’t associate with felon rule enforced for family’s?
Would they insist that a father and son remain apart?
For family’s what? 
Exceptions to that rule are made for families or friends or employers, on a case by case basis. Just as they are made for prison workers who have a family member or friend who ends up under the supervision of the Dept. of Corrections.
I hadn’t considered prison staff.
Hi brother! Would be a bit awkward if he is an inmate.
Google found this answer. Several attorneys responded. I quoted the best answer.
Qadgop correctly pointed out exceptions can be made under the right circumstances.
https://www.avvo.com/legal-answers/can-person-on-felony-probation-and-a-convicted--fe-2138341.html
merely an anecdote, but my ex-sister-in-law related to us that there were “whole families” of two, and in one case three generations from the same family in the same facility when she was a prison guard.
Can I use that on my next Hallmark card?
The family that preys together stays together.
Or the family that has alcohol or addiction issues often gets sent to prison rather than getting the medical help they need.
Stick that in your Hallmark card.
I guess you’re having a bad day.
That was the most innocuous joke imaginable. A harmless play-on-words with the proper emoticon.
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Afraid I’m with Q on this one, Ace. And I’m very glad he got there before me.
Patterns of abuse, addiction, and just plain bad socialization are allowed to run rampant in our society. The reason European countries have so much less crime per capita is that in those countries these problems are addressed, rather than merely punished.
I would not go that far, reality is that our support services in the UK have taken a nosedive, all due to the need to ensure our banks do not go under - the result is a public spending austerity cut.
You will not be surprised to learn that our crime rates are rising.
We had planned to demolish a number of prisons with poor facilities so they could be replaced with new builds, well that has been delayed - some of the rebuilds will go ahead because they were already too far committed, but a number of them have been postponed. All because our prison population is rising beyond expectations.
Except that if you cut the numbers of police, if you cut the numbers working in prisons and if you cut education provision, drugs support, mental health provision etc then you can expect recidivism to increase - sometimes ‘efficiency savings’ are the most expensive forms of expenditure you can make.
Looks like we are well on the way to the American model