Abraham Lincoln was born 210 years ago today. That much we know for sure. But there are plenty of questions about his origins that still puzzle historians.

“Lincoln’s birth and the circumstances of where he came from is a real central part of the popular Lincoln story,” says Christian McWhirter, Lincoln historian at the Abraham Lincoln Presidential Library and Museum. “The idea of Lincoln coming from these extremely humble origins and not only rising to the presidency, but also saving the nation, they’re a key element of what Lincoln represents for America and American history.”

The oft-told story of Lincoln being born in a log cabin is true. According to David Herbert Donald’s biography, “Lincoln,” the 16th president was born on a 300-acre farm on Nolin Creek near the modern-day town of Hodgenville in north-central Kentucky. He was born in the family home, a 16-feet by 18-feet log cabin. “The sturdy building, which had only a dirt floor and no glass window, was as large as about 90 percent of the pioneer cabins of the region,” wrote Donald.

“It would be nice if we still had the log cabin,” says McWhirter. “The log cabin at the (Abraham Lincoln Birthplace National Historic Park) is representative. No one knows what happened to the actual cabin.”

Abe was the first president born west of the Appalachian Mountains, according to the National Park Service. It operates the Abraham Lincoln Birthplace Historic National Park in Hodgenville, near the Lincolns’ so-called Sinking Spring Farm, where he was born.

Lincoln’s father was Thomas Lincoln, described in different accounts as a farmer and carpenter, and his mother was Nancy Hanks. The couple already had a daughter named Sarah when Abraham was born. He was named after Thomas’s father, according to University of Illinois Springfield Lincoln Studies Professor Michael Burlingame’s book, “Lincoln: A Life.”

Lincoln didn’t remember his birthplace because his family moved when he was about two and a half years old. Historians wish he had remembered it and other details about his origins. In Burlingame’s online version of his book, he cites a woman who said she was present at Lincoln’s birth and described the family’s cabin as very meager, with a “bear skin” for a bed blanket.

“One of the arguments that historians have had to deal with is, was Lincoln truly brought up in real poverty,” he says. “Nobody on the frontier was really prosperous, but were the Lincolns, as some people would like to argue, members of the frontier bourgeoise? But there’s so much evidence we have from testimony from all kinds of different people that while everybody on the frontier was poor, the Lincolns were really poor.”

Another mystery is Lincoln’s father. The question is “whether his father was an industrious and responsible fellow or rather shiftless,” Burlingame says. “I fall into the latter category in interpretation because there’s so much testimony from his neighbors and relatives (that) he was basically a good-natured fellow, but he was not ambitious, and he discouraged his son from acquiring an education, really wasn’t very close to his son and didn’t treat him very well.”

McWhirter says, “I wish we had more evidence from his parents. We need writings or letters from Thomas and Nancy. Thomas apparently couldn’t write. He could scrawl his name, but we think that’s maybe all he could do. So, we hear about Thomas and Nancy mostly through other people, and a lot of that is controversial — was Thomas a ne’er do well or wasn’t he? It would be nice if we could have Thomas speak for himself.”

“Lincoln fantasized that his mother’s father was a Virginia aristocrat and he got all of his ambition, talent and intellect from his grandfather on his mother’s side,” Burlingame says. “But we don’t know who that grandfather was.” It’s just another Lincoln mystery.