Some sources say he and his wife had one child, while others do not mention any.
Charles Darwin- organic evolutionWilliam Harvey- mechanis of human blood circulationRobert kock-discover bacteris causing anthrax,tubercolosis,and choleraAnton van leeuwenhoek-discovered microscope first to observe spermatozoa
While he and his wife may have had children, they are not mentioned in any articles about him, nor in his obituary.
1 kilogram equals 2.2 pounds. Only some sort of small model cycle would weigh this little.