Many of us have shared your concern. I've now come to the conclusion that it may not be warranted.
Refer to post #97, this thread. It links to a short series of these two women, Deborah Frisch and Cecile McKee shown with a dog. Judging by the appearance of the two women, these pictures were taken at an earlier date than the one you commented on.
The absence of a child in these earlier photos is interesting. If the photo with child is more recent, then one of the two would have had to have birthed that child subsequent to the earlier photos (if the child was in existence at the time of the earlier photos why wasn't she included?). The fact that they were 'partners' in both sets of photos means that one of the two admitted lesbians would have had to have birthed a child during their relationship; something not very likely IMHO.
Obviously, someone was also in the kitchen taking the photo. We don't know the provenance of the photo, but it's possible to assume that the child belongs to someone else who happened to be in the house when the kitchen photo was taken. Of course, all this is speculation, but makes as much sense as that 'young' child belonging to one of these women.
Just my two cents worth.
Maybe not very likely, but still possible with in vitro fertilization. Example: Melissa Etheridge and Julie Cypher (sp?), with David Crosby being the sperm donor.