Over a career of consulting with family businesses, including very large ones, I came to know many CEOs who rose to the top of the business the way that Donald Trump did: by being the son of the founder and thus the heir-apparent. (All of them were men.)

It’s more than a coincidence that a majority of them had similar behavioral traits and leadership styles as Trump does. They steamrolled over others, bristled at criticism, didn’t resolve conflicts effectively, had high ego needs, and created chaos by making decisions impulsively and unilaterally. Whatever their business acumen, they weren’t good at listening, consensus-building, and teamwork.

Their bad behavior wasn’t due to an inherent personality flaw. It was due to their development being stunted. Unlike executives who rise to the top of public businesses, the offspring of the founders of family businesses are treated differently by coworkers during their career. Even if they start their career in the mail room, everyone up and down the chain of command knows that they have direct communications to dad, will eventually be their boss, and have the influence and power to make or break their careers.

As a result, the heir-apparent doesn’t get helpful feedback in his formative years in the business, doesn’t develop political skills, and doesn’t learn how to get the support of others to get ahead. He has to please only one person: dad.

By contrast, successful non-family executives learn valuable lessons early in their careers, usually the hard way, by making mistakes, especially such political mistakes as blindsiding a boss, or bruising the ego of an important colleague, or grabbing the wrong coattails. This is why most executives at large companies tend to look the same and sound the same. They have learned to weigh their words carefully, to modulate their tone, to keep their emotions in check, and to patiently listen to counter opinions.

Politicians who have risen through the ranks of retail politics also tend to have similar characteristics. Whether they are the president of France, or the president of China, or a U.S. Senator, or a governor, or a mayor, they are measured in what they say and how they act. Likewise, they are careful not to make any more enemies that necessary, they try to reach compromises with opponents and build coalitions, they are thick-skinned, and they hide their Machiavellian tactics behind a demeanor of affability and a carefully crafted public persona. In other words, they are the opposite of Trump.

Trump’s stunted development in business is now catching up to him in the Oval Office. His propensity to insult people and make enemies, coupled with his thin skin and vindictiveness, is severely harming his presidency.

The irony is that many people though that Trump’s business experience would be his greatest asset as president. Actually, it is his greatest liability.