Family is one of those odd words that can be looked upon as a singular noun or as a collective singular noun (like police).
If you view family as one single unit, you can use the 3rd person singular verb as Vincent did in his sentence.
If you view family as all the individual members of that group together, you opt to use the verb in 3rd person plural as you did in your sentence, Tanguatlay.
In some situations, I think the singular is more appropriate than the plural verb form. In Vincent's sentence I view it like that.
Let's say you've invited all the members of your extended family to a big dinner party. The members of the family live in different parts of the city and some even live in the suburbs. In a situation like that, I can easily see how somebody would say I'm having a dinner party on Saturday night. The family are coming and a few special friends, too.