The Willis is composed of two sisters, Dorothy Willis and Helen Willis.

William Crawford Williamson was born on November 24, 1816, in Scarborough, Yorkshire, England.

He was an English physician, naturalist, paleobotanist, and author. He studied medicine at University College, London, and during his studies, he acted as curator of the Natural History Society's museum at Manchester. After his graduation in 1841, he returned to Manchester to practise his profession. In 1851, he became Professor of Natural History at newly founded Owens College in Manchester and retained the chair of botany until 1892. Williamson was also a successful popular lecturer, especially for the Gilchrist Trust. He was elected a Fellow of the Royal Society in 1854, winning its Royal Medal in 1874 and delivering the Bakerian Lecture in 1877. He received an honorary LL.D. degree from the University of Edinburgh in 1883 and the Wollaston medal of the Geological Society in 1890. He published numerous articles and papers on paleobotany.

In 1842, he married Sophia Wood (1818–1872), and in 1874, he remarried Ann Copley Heaton (1842–). He died on June 23, 1895, in Clapham, London, England.

Sophia Williamson was the daughter of William Crawford Williamson and his first wife, Sophia Wood.

Solicitor and anthropologist Robert Williamson was born into the Lancashire family of British geologist Professor Willliam Crawford Williamson. Privately schooled, he continued his education at Owen College, where he graduated in engineering, then studied law at Clements Inn where he was “prizeman” at his final exams in 1897. His wife, Emily, whom he married in 1882, was a co-founder of the Royal Society for the Protection of Birds. Law occupied him for the next decades as a solicitor in Manchester from 1879 to 1908. During this time he was president of the Manchester Law Society and a member of the London Law Society (1902), and from 1903 to 1910, a member of the court of governors of Victoria University of Manchester. He had been friends since 1908 with the anthropologist and zoologist Alfred Haddon and, abruptly changing career directions, turned to the field of anthropology at age 54. In 1910 he participated in the Cambridge expedition that Haddon led to the Torres Strait and British New Guinea. He eventually wrote six books on New Guinea and Polynesia .He was honorary treasurer of the Royal Anthropological Institute from 1912 to 1921 and vice-president of the institute from 1925 to 1927. Owens College bestowed on him an honorary M.Sc. in 1913. His major work was three volumes on The Social and Political Systems of Central Polynesia, the last volume of which was published posthumously.

Annie Copley Heaton was born in 1842 in Hunsley, Yorkshire. She married William Crawford Williamson in 1874, in Bradford, England.

Alexander William Williamson was born on May 1, 1824, in Wandsworth, London, England.

He was an English chemist. He studied at the University of Heidelberg, University of Giessen (Ph.D., 1845) and spent three years in Paris studying higher mathematics under Auguste Comte. In 1849, he was appointed Professor of Analytical and Practical Chemistry at University College, London. In 1855, Williamson became the chair of general (theoretical) chemistry, a position he held until his retirement in 1887. He is credited for his research on the formation of ether by the interaction of sulphuric acid and alcohol, known as the Williamson ether synthesis. In 1855, Williamson became a Fellow of the Royal Society, and in 1862, he received a Royal Medal for his work on etherification. He also served as its foreign secretary from 1873 to 1889. He was twice president of the London Chemical Society (1863-1865, 1869-1871).

In 1855, he married Emma Catherine Key (1831–1923). He died on May 6, 1904, in Hindhead, Surrey, England.