With the Supreme Court set to hear testimony on same-sex marriage cases this week there has been a lot of talk about how the demographics is destiny for the issue. Many have pointed to that a new Washington Post poll that found 81 percent of adults under the age of 30 support marriage equality, which means it is only a matter of time before it is approved.

Data from Quinnipiac

It is worth remembering that the exact same dynamic holds true for marijuana legalization, even though its inevitability is not discussed as much. For years the polling on same-sex marriage has almost mirrored that for marijuana legalization. Both are subject to the same generational divide that makes eventual success inevitable as the opposition slowly dies off.

Back in December Quinnipiac ask about marijuana legalization and same-sex marriage in the same poll. As you can see, the demographic breakdown was nearly identical.

It is not just coincidence that last year Washington State was one of the first states where voters approved same-sex marriage and marijuana legalization. Both were approved by similar margins, 53.7 percent yes for marriage and 55.7 percent yes for marijuana.