1. There is no such certificate called "Family Tree" issued from any Government Office in any mode. The importance of the family tree is to know who are having rights on the property and who are the successors. If you can trace the first owner's heirs and obtain Legal-Heirship certificate (it will work-out only if the said owner is no more), it may be possible to get the family tree.
2. You should find out the chain of ownership upwards from the original buyer. The title deeds alone would throw light on the chain of ownership. Ownership flows out of title deed, not family tree. The due diligence test has to pass through many stages such as finding out whether a dispute is pending in any court of law with respect to the property to be purchased, whether the construction is in accordance with master plan, whether the requisite permissions have been obtained,etc. Property purchased without proper due diligence is an invitation to a long drawn legal battle.