Zaid Alsalami, Shaykh Dr Zaid Alsalami is an Iraqi born scholar, raised in Australia. He obtained a BA from Al-Mustafa University, Qom, and an MA from the Islamic College in London. He also obtained a PhD from... Answered 2 months ago

Bismihi ta'ala

In our Shari'ah, we do not have any prohibition or censuring of marriage of a Seyid/Seyidah to a non-Seyid/Seyidah. This is a cultural practice and personal preference of a parent. 

One must bear in mind though that if one is to marry a Seyid/Seyidah, they must stress on a higher level of honouring and respecting them, due to their lineage to Ahlul Bayt (a.s.). 

As this is a frequently asked question, please refer to other answers given on this:

Zaid Alsalami's response to Is a female Sayed allowed to marry a non-Sayed male? (al-islam.org)

And:

Zaid Alsalami's response to Is it true that Imam Khomeini's daughters are married to non-syed Muslims? (al-islam.org)

And Allah knows best.