Credit: Neilson Barnard/Getty Images Photo: Donald Trump Jr. and Vanessa Trump at the Celebrity Apprentice Season 4 Finale in New York City on May 22, 2011

Looks like Donald Trump's six grandchildren are about to lose a fraction of their inheritance! The infamous business tycoon is about to become a grandfather for the seventh time, as Vanessa and Donald Trump Jr. are expecting their fifth baby.

Donald Jr. broke the news on Twitter, writing, "Well, @MrsVanessaTrump, Kai, D3, T-Man, Spencer, and I have some exciting news. We are expecting baby #5 this summer. Cant wait #evenlesssleep."

The progeny to which he refers there is the couple's six-year-old daughter, Kai, and their sons: four-year-old Donald III, two-year-old Tristan, and 15-month-old Spencer.

Meanwhile, those kids have two cousins — Ivanka Trump's two-year-old daughter, Arabella, and her three-month-old son, Joseph.

Donald Jr. and Vanessa, a model, married in 2006. And we bet you can guess the proud father's line of work! He, Ivanka, and their brother Eric are all executive vice presidents at The Trump Organization.

All three of those siblings are children of Donald's first wife, Ivana Zelníčková. Donald since married and divorced Marla Maples (with whom he has a daughter, Tiffany) and married Melania Knauss (with whom he has a son, Barron). Sounds like Big Don really goes for women whose name ends in "a."

In any case, congrats to Donald Jr. and Vanessa — and our condolences to the rest of the heirs on their marginally-smaller payout.

Dan Clarendon is an assistant editor at Wetpaint Entertainment. Follow him on Twitter and Google+!