'Think before you tweet' has become an important lesson for the Trump family, especially as his in-laws take to social media to support the Republican during the Presidential campaign.

Lara Trump, one of the heiresses of the real estate tycoon’s fortunes, "liked" a tweet posted on Friday by a group called “Fascists 4 Trump”, which linked to an article strongly questioning his business success.

Lara Trump, who married Donald Trump’s younger son Eric in November 2014, posted enthusiastic tweets about her father-in-law following the sixth Republican debate on Thursday night, and liked other tweets that shared her enthusiasm.

One "like" by the personal trainer turned CBS producer, however, appears to have been misplaced.

The tweet, posted by “Fascists 4 Trump”, links to a Quora article by Kevin Flint that questions Mr Trump’s business savviness.

The article quotes a piece in Fortune which demonstrated that Mr Trump's wealth has failed to beat that of an index fund which simply aims to track the stock market.

"So not only would I say Trump isn't a business genius, but Trump isn't even close to being the best business minded reality television star. He is thoroughly trumped by a very successful woman [Paris Hilton] dismissed by many as “vapid,” “naive,” “stupid” and far worse insults," the Quora article reads.

"Fascists 4 Trump" is a parody Twitter account with a Nazi swastika plastered over the picture of Mr Trump's face.

Mr Trump said in the debate on Thursday evening that he would not wish to rethink his position on banning all Muslims from the US, and focused in on competitor and Canadian-born Ted Cruz's citizenship.

Speaking about US policy on Muslim immigration, he told the audience: "We are being laughed at all over the world."