Kamin was a male native of the planet Kataan circa the 14th century. He was an "ironweaver", and an amateur musician who played the flute. Before his world's sun went nova, his memories were uploaded into a interstellar probe and sent into space, along with his flute, in hopes that some memory of their people would live on.
In 2368, the USS Enterprise-D encountered this probe, which initiated a memory transfer with Captain Jean-Luc Picard. In the span of 30 minutes, Picard experienced 42 years of Kamin's life, including his marriage to Eline and the birth of their children. Following this incident, Picard retained Kamin's ability to play his flute, which had been retrieved from the probe. (TNG episode: "The Inner Light")
Picard's experience as Kamin -- in addition to his assimilation into the Borg Collective as Locutus, and his mind meld with Sarek -- created a mental state similar to Multiple Personality Disorder. This state enabled Picard, in 2370, to resist the Chova, a telepathic weapon being used against the Enterprise crew by a faction of the Damiani. (TNG comic: "Perchance to Dream")
Picard struggled with Kamin's memories of fatherhood in 2380, when his wife, Beverly Crusher, suggested having children of their own. Having experienced the loss of a child through Kamin's memories, Picard was hesitant to repeat the experience. He eventually overcame these issues and did conceive a son with Beverly. (TNG novel: Greater Than the Sum)