Published: May 6, 2009

Ryan Kramer, an 18-year-old who is graduating May 8 from the University of Colorado at 麻豆影院, is no stranger to national publicity.

"Oprah," "60 Minutes," "Good Morning America," USA Today, Time magazine and many other mainstream media outlets have told his story about being conceived through an anonymous sperm donor and his quest to find his half-siblings and help match other people with their half-siblings.

"I was told that I was donor-conceived at a very young age, and as long as I can remember I have been curious about who my biological father was," Kramer said. "My mom and I are also very big proponents of openness and honesty in this process. For me, it's who I am, and it's not a good thing or a bad thing, it's just who I am."

Through research he and his mom learned that anonymous sperm donors often donate multiple times, meaning that there are many half-siblings out there. So in 2000 he and his mom started a Web site called the Donor Sibling Registry at .

"We started it to see if anybody else was out there who was curious like I am about being donor-conceived," Kramer said.

Kramer's story received some local coverage in the media, and then it really took off. He and his mom appeared on "Good Morning America," "60 Minutes," "Oprah" and just about every show you can think of, Kramer said. The huge amount of media attention helped bring people to the Web site which today has more than 25,000 registered members.

"We have nearly 6,500 people who have made matches with each other," Kramer said. "These are, for the most part, half-sibling to half-sibling matches, but also matches between children and their donors. It's been really cool because it is a mutual consent site. People only come on if they want to be found."

Kramer said learning about his sperm donor helped answer some of his questions about his school interests.

"As long as I can remember I had a curiosity about airplanes and space," Kramer said. "Most everybody on my mom's side of the family has more of a liberal arts background, but my sperm donor is an engineer and his father was an engineer and his father was an engineer. On my paternal side I come from a long line of engineers, so I inherited this very mathematical, scientific type of brain, and it has always attracted me to science and engineering."

And it's aerospace engineering that has kept Kramer busy at CU-麻豆影院, where he entered school at a very young age.

"I came to CU when I was 14," Kramer said. "At first it was intimidating. It took me a little while to settle in and get comfortable. The challenge of fitting in was difficult at first."

In high school he often was bored with his courses, but that changed when he arrived in college.

"When I came to CU I felt overwhelmed by the level of intensity of the academic competition," Kramer said. "That was a good thing because it was the challenge I was looking for."

Most recently he has been working on his senior project, which is a solar-powered unmanned aerial vehicle, an airplane that uses solar power to try to achieve indefinite flight. It charges its battery with solar power during the day and then flies through the night on that charge.

Kramer is interested in unmanned vehicles as well as alternative energy.

He will head to the University of Southern California in the fall to work on a master's degree in engineering management, which will give him the skills he needs to take his knowledge to the next level.

"I want to take ideas and make them into the realities of real products and real businesses," he said.

But shortly after his May 8 graduation, Kramer has an important trip to take.

"I have been able to locate seven half-siblings, and have been able to meet one so far," he said. "After graduation I will be traveling to New York to meet two of my half-siblings who I found recently."

Kramer said the support that his mom always gave to him when it came to his curiosity about his paternal roots is really important to him.

"My mom has been awesome and so supportive of my curiosity," Kramer said. "This really is a big part of my life, and our efforts are something I am very proud of."

A photo slideshow can be viewed on the CU-麻豆影院 News Center at /.