of his research; Biographer Jonathan Gathorne-Hardy explains that this was done to ensure the films' secrecy, which would have caused a scandal had it become public knowledge. James H. Jones, author of Alfred C. Kinsey: A Public/Private Life, and British psychiatrist Theodore Dalrymple, among others, have speculated that Kinsey was driven by his own sexual needs. Some of the data published in the two Kinsey Reports books is controversial in the scientific and psychiatric communities, owing to Kinsey's decision to interview volunteers who may not have been representative of the general population. University of Chicago sociology professor Edward Laumann also argued that Kinsey's work was focused on the biology of sex and lacked psychological and clinical information and analysis. Kinsey collected sexual material from around the world, which brought him to the attention of the U.S. Customs Service when they seized some pornographic films in 1956; he died before this matter was resolved legally. Kinsey wrote about pre-adolescent orgasms using data in tables 30 to 34 of the male volume, which report observations of orgasms in over 300 children aged from two months up to fifteen years. This information was said to have come from adults' childhood memories, or from parent or teacher observation. Kinsey said he also interviewed nine men who had sexual experiences with children and who told him about the children's responses and reactions. Little attention was paid to this part of Kinsey's research at the time, but where Kinsey had gained this information began to be questioned nearly 40 years later. It was later revealed that Kinsey used data from a single pedophile and presented it as being from various sources. Kinsey had seen the need for participant confidentiality and anonymity as necessary to gain "honest answers on such taboo subjects". Years later, the Kinsey Institute said that the data on children in tables 31–34 came from one man's journal (started in 1917) and that the events concerned predated the Kinsey Reports. Jones wrote that Kinsey's sexual activity influenced his work, that he over-represented prisoners and prostitutes, classified some single people as "married", and that he included a disproportionate number of homosexual men, which may have distorted his studies. While he has been criticized for omitting African-Americans from his research, his report on the human male includes numerous references to African-American participants. Historian Vern Bullough writes that the data was later reinterpreted, excluding prisoners and data