Conjugal visits for prisoners?

The Economist magazine has an article stating that many countries have recently introduced conjugal visits for prisoners.  

In September Qatar’s Central Prison unveiled villas for spouses and children to visit married inmates. Turkish prisons introduced them for the first time earlier this year. Authorities in Costa Rica, Israel and Mexico have in recent years allowed them for homosexual inmates. Even Saudi Arabia and Iran have long allowed them for married prisoners. And many Latin American countries allow private visits for unmarried inmates too. . . .

Will the US Supreme Court start looking to foreign countries for guidance on this point?  Apparently, five American states also allow these visits.  The claimed benefit is that it makes it easier to control prisoners.  But what doesn't get discussed is that this might make prison less of a punishment and thus reduce deterrence.  What is the net effect?  I don't know.  But it seems something that should be discussed.  Some argue that criminal predisposition is genetic so there is also the issue of whether certain types of people, particularly those with long violent criminal histories, should have kids.