I can see where there may be some uncertainty about the donor's date of acquisition when the gift is a fruitcake, but you asked about a home.  How many people accept real estate without knowing how long their benefactor owned it?  And that's always public record, and most deeds are online these days. 

The Form 8949 instructions are silent about what to enter as acquisition date for a gift.  I think it's safe to use the date that determines whether it is short term or long term.