Re: Emmerdale
Apropos the Vanessa being a lesbian storyline, she had developed feelings for her friend, but never actually acted on them so I do not think this qualifies her as being a lesbian. As for Ali, I think it was a combination of excess booze, and the deep emotional crisis she was experiencing over Sean, creating a strong need for comfort (hence the cuddle/hug). From there, familiarity and 'muscle memory' took over.
As for people either being lesbian or not, I think this is a grey area. Emotions and emotional attachments are funny things, women more than men, can be governed by their emotions which can result in a close friendship developing into more. Sometimes this is reciprocated, as with Ali and Ruby, and other times it is not, as with Vanessa and Rhona. Even when it is reciprocated and a relationship develops, this does not necessarily mean a person is lesbian for life though, that relationship could end and the girl/woman find she never feels that 'pull' towards another woman.