Genealogists are interested in half-siblings (and who each one's parents were) as well as full siblings. That requires some way of indicating children by different partners. Familypedia, using semantic extensions, has http://familypedia.wikia.com/wiki/Template:Siblings.(which is a shortcut to a longer pagename). (It lists partners of the father by default; it needs a parameter added if only the mother's page lists the children; and it needs a repetition with different parameters if there were half-siblings from both parents.) Example article at http://familypedia.wikia.com/wiki/Heather_Campbell_(1911-2004) ~~~~
Topic on Extension talk:Genealogy
This is a very good idea. At the moment it lists full and half siblings alongside each other and doesn't distinguish between them at all. However, with the addition of some more variables that can be used in
Template:Person/list-item it should be reasonably easy to mention the parents (in parentheses, say) along with each sibling, if they differ.
I'll look in to adding this.