It's understood that United expressed interest in signing the highly sought-after defender following their Europa League triumph over Ajax in 2017.
But, on the advice of senior recruitment members, United's interest dwindled based on the concern that 19-year-old would eventually become overweight. This theory was allegedly based on his family history.
De Ligt has gone on to establish himself as one of the most promising young players in the world after playing a prominent role with an Ajax side the defied expectations to reach the Champions League semifinals this season.
As a result of his exceptional season with the Dutch outfit, De Ligt has caught the attention of some of Europe's biggest clubs.
Barcelona are reportedly leading the race to sign De Ligt, who Ajax DEO Edwin van der Sar admitted would likely depart this summer.
If he does leave, De Ligt will look to go out as a champion as Ajax sit atop the Eredivisie table thanks to their superior goal difference over second-place PSV Eindhoven. Both teams have 80 points with two matches remaining.