Growing up in Minneapolis, Prince and Duane Nelson went to the same school, played on the same basketball team and hung out with the same group of friends. People considered them to be half-brothers. And many assumed they shared a father — John L. Nelson.

But did they?

Millions of dollars for the late Duane Nelson's daughter and granddaughter hinge on the answer.

In the 3 ½ months since Prince died — apparently without a will — of an accidental overdose of the painkiller fentanyl, the nature of his relationship with Duane Nelson has become a key point in determining who is ultimately entitled to share a piece of the late musician's $100 million to $300 million estate.

Carver County District Judge Kevin Eide, who is overseeing the estate case, partly clarified that question last week when he narrowed the list of potential heirs from more than two dozen to just eight. Of those remaining, he ordered genetic testing for six believed to be descendants of John L. Nelson — including Duane Nelson's daughter and granddaughter — to determine if they are related to Prince.

Though this case is unusual because of Prince's celebrity, the genetic testing aspect is not, said University of Minnesota Law School Prof. Judith T. Younger.

"This goes on all the time, but on a smaller level," Younger said. "In fact, I would say one of the five most frequently underlined reasons for genetic tests are inheritance questions."

Dozens of people with claims on Prince's estate emerged in the days, weeks and months after he was found dead on April 21.

In large estates and celebrity cases, "it's common to have people come out of the woodwork and either legitimately or mal-legitimately claim to have some right of inheritance," said Laura Zwicker, a Los Angeles attorney who represents individuals with more than $100 million in assets.

The first purported heir to be eliminated through genetic testing was Carlin Q. Williams, a Colorado inmate who claimed to be Prince's son.

Eide nixed 20 others last week, including five who suspected they might be the musician's half-siblings, two claiming to be his children and a woman who argued she was secretly married to Prince.

Not a 'real Nelson'?

Barring additional claims or challenges to the judge's ruling by potential heirs and their attorneys, the issue now comes down to the final eight — and the questions surrounding Duane Nelson.

Bremer Trust, the special administrator overseeing the estate, said early on that certain potential heirs might need to substantiate their claims through genetic testing.

Attorneys representing Duane's two descendants — 31-year-old Brianna Nelson and Victoria Nelson, the 11-year-old daughter of Brianna's deceased brother — pushed back, arguing that Minnesota law doesn't limit heirs to proving their family connections that way.

But other means of proving the relationship have been complicated by disagreements over the relationship between Prince and Duane, who were born just two months apart but who have the same father — John L. Nelson — listed on their birth certificates.

According to a sworn statement from Carmen Denise Weatherall, Brianna Nelson's mother, John L. Nelson and his daughter Norrine Nelson visited Duane's apartment in Milwaukee in 1981.

"I recall John Nelson being a quiet and reserved man who was loving toward Duane," Weatherall's statement said. "John Nelson spoke with great pride about Duane's success at basketball and college."

And yet, she said, she also heard Norrine tell Duane that he was not a "real Nelson." She recalled that John and Norrine fought about it, and he insisted that Duane was his son.

When John Nelson died in 2001, Duane was not among those listed as an heir. Sharon Nelson, Norrine's sister, said in a sworn statement that "Duane Nelson was not determined to be the son of John L. Nelson." Duane died in 2011 at age 52.

A family tree

After Prince died, his only full sibling, Tyka Nelson, filed probate documents that listed one deceased half-sister, Lorna Nelson. That filing excluded Duane Nelson as an heir apparent.

Here is the back story: On Oct. 29, 1938, John L. Nelson married Vivian Howard. They eventually had four children — John, Norrine, Sharon and Lorna — and lived together in a house in south Minneapolis.

Court records paint a picture of a family that went to church, danced, sang and played games together. They traveled to Taylors Falls, where they smiled for a photo around a picnic table full of food.

In a sworn statement, cousin Joseph Daniel Camp Jr. of Edina recalls that he "always looked forward" to visiting the Nelson family home.

"Uncle Johnny would typically entertain us by playing the piano and singing songs," he said. "For my family and myself, Uncle Johnny's piano playing was always the highlight of our visits."

But around 1956, Camp said, "Uncle Johnny was no longer living at the Nelson family home."

John and Vivian divorced in March 1957. Five months later, John married Mattie Shaw. In June 1958, Prince Rogers Nelson was born. That August, Duane was born to Vivian Howard.

Now, all three men and both women are dead.

Millions in the balance

While the value of Prince's estate has yet to be determined, estimates have ranged from $100 million to $300 million.

Under Eide's order, genetic testing will decide if Brianna Nelson and Victoria Nelson stand to benefit at all. The answer could make a difference of several million dollars for the other heirs.

If it turns out that Prince has a child, however, then all bets are off. Under Minnesota law, he or she would inherit everything.