We've Got Twins in the Fam Now!!!

Exclusive

Caitlyn Jenner has 2 new grandchildren -- Brandon Jenner and his wife are the proud new parents of twin boys!!!

Brandon and Cayley Stoker just registered birth certificates for the twins with Los Angeles County records. The documents say the bundles of joy arrived on Wednesday, February 19.

The couple knew they were going to have twins -- they announced that back in August -- but remember ... they said they didn't want to know the gender before they were born. Sorry, no fancy gender reveal parties for them.

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Brandon and a very pregnant Cayley tied the knot last month at the Santa Barbara Courthouse -- and earlier this month, Cayley had her baby shower in Malibu. We're still trying to find out if they've named the boys yet.

BTW ... Brandon's the son of Caitlyn and Linda Thompson. He already has a daughter, Eva, from his first marriage to Leah Felder.

The twins bring Caitlyn's grand total on grandkids to a whopping 18!!!