It is undoubtedly going to be the case that same sex marriage will expand the variety and range of the kinds of family relationships that will occur and we might as well be prepared for them. This is an excellent film that looks at one particular aspect of it.

This 2010 film stars Annette Bening and Julianne Moore as a lesbian couple who have been together a long time. They each have one child that they gave birth to by artificial insemination, Bening’s daughter being now 18 and Moore’s son being 15. They are pretty much your standard well-to-do suburban family with Bening a physician and Moore a stay-at-home mom who has decided to start a new landscaping business now that the children have grown, and they have to deal with all the normal issues that couples have with each other and with their adolescent children.

The key plot point is that the sperm donor is the same in both cases, making the children stephalf-siblings and they decide one day to contact their biological father, played by Mark Ruffalo. He dropped out of college and is now the successful owner of a small local restaurant while retaining a laid-back attitude, wearing casual clothing and riding his motorcycle. After the two children clandestinely meet their father and decide they like him, they reveal the news to their parents who decide to invite the biological father of their children to lunch so that they too can get to know him. The rest of the film deals with the complicated situations that develop.

What I liked about this film is that the story is engrossing without having to resort to the usual plot devices to create comedy or drama. None of the characters are evil or even nasty, deliberately trying to hurt or destroy others. All the characters are basically decent people who want to do well by the others. The most common device that is used for both comedy and drama, obnoxious and bratty kids, is not used which is wonderful because I hate that with a passion. Both children are normal, trying to please their parents while chafing under their protectiveness because they, like many parents, are unable to quite recognize their children’s growing adulthood and independence.

Things get complicated and threaten to fall apart simply because of the tensions that arise when a new person becomes part of a long-standing family in which the relationships have already been cemented. The newcomer has to walk a fine line between being too distant and aloof and moving too quickly and assuming the same rights as the other adults. This is similar to the situations in which a step-parent enters a family except that in this case the line Ruffalo has to walk has been made even finer by the fact that all three adults have a biological connection to the children.

The film reminds us of a point that is often overlooked in the heated debate over the issue of same sex marriage. It is not primarily about what kinds of sex people have. It is about the right of people to choose whom they want to have a long-term familial relationship with. But I think it is the thought of gay sex that drives opponents of same sex marriage batty. An interesting experiment would be to see if there was equal opposition to same sex marriage between two people who vowed to remain celibate, say two Roman Catholic priests or two nuns. Alas, that is a hypothetical that is unlikely to ever be tested.

The family dynamics in this film will feel familiar and routine to most people. Writer and director Lisa Cholodenko was clearly trying to make the point that families headed by same sex parents are not that different and face many of the same issues and respond in the same way as those having parents of different sexes, but with a few new wrinkles. She succeeded.

The film definitely benefits from first-rate acting performances from the five principals, none of whom overplay their roles. Bening acts in few films and each time I see her every few years or so, I am blown away by what a good actress she is. She easily ranks up there with the top character actresses, arguably even better than more acclaimed ones like Helen Mirren and Meryl Streep.

Here’s the trailer.