The rule according to rig Veda is that one cannot share a common paternal ancestor for 7 generations and maternal ancestor for 5 generations.
I had encountered this in a book on Rig Veda, but I am not able to recollect it.
Also Manusmriti 3.5 says:
"Marriage should he performed with persons not belonging to the same Pravara;—above the Seventh grade ...
𝐒𝐤𝐚𝐧𝐝𝐚 𝐏𝐮𝐫𝐚𝐧𝐚, 𝐀𝐯𝐚𝐧𝐭𝐢 𝐊𝐡𝐚𝐧𝐝𝐚, 𝐑𝐞𝐯𝐚 𝐊𝐡𝐚𝐧𝐝𝐚, 𝐂𝐡𝐚𝐩𝐭𝐞𝐫 𝟓𝟎 - 𝐑𝐮𝐥𝐞𝐬 𝐚𝐛𝐨𝐮𝐭 𝐭𝐡𝐞 𝐄𝐥𝐢𝐠𝐢𝐛𝐢𝐥𝐢𝐭𝐲 𝐟𝐨𝐫 𝐃ā𝐧𝐚.
कन्यादानं कथं स्वामिन्कर्त्तव्यं धार्मिकः सदा ।
परिग्रहो यथा पोष्यः कन्योद्वाहस्तथैव च ॥ २७ ॥
O Lord, how is the gift of a virgin(Kanyadana) to be made by ...
In ancient India, parents of a girl used to demand dowry unlike now when the opposite is the case. This practice is severely criticized in Hindu scripture.
Condemnation of dowry
A wife should never be purchased. Nor should a father sell his
daughter. Only those persons of sinful soul who are possessed,
besides, by cupidity, and who sell and purchase female ...