MARBLEHEAD – In an unusual election event, the son of a Board of Health member is seeking the seat that his father will vacate in May.Dr. Todd Belf-Becker, a dentist and lifelong resident of Marblehead, has filed nomination papers for the Board of Health seat currently occupied by Dr. David Belf Becker, a dentist who is stepping down after 18 years on the board.It is not unusual for the son or daughter of an elected town official to seek office – Selectman William Woodfin II is the son of the late Cemetery Commissioner Benjamin Woodfin – but it is unusual for a son to seek the office that his father is vacating.”This is the first time I’ve seen it happen since I’ve been working in the office,” said Town Clerk Robin Michaud.The deadline for taking out nomination papers is March 24 and so far Todd Belf-Becker is running unopposed.Todd is the son of David Belf Becker – “Belf” is David Becker’s middle name – and Selectman Jackie Belf-Becker. Selectman Belf-Becker, who is seeking re-election, is a lawyer. She has served on the Board of Selectmen since 2004 and before that she served on the School Committee for eight years, from 1988-1996. She and her husband have a daughter, Kate, who lives in Brookline.Todd is single and lives in Marblehead. A 1997 Marblehead High graduate, he has degrees from Indiana University and Tufts University Dental School.He said Tuesday he never discussed running for office with his father. “I came to the decision on my own,” he said. “I always wanted to do public service and I’m in a health profession. It just made sense.””I’m very passionate about the environment and recycling,” he said. “Everybody lives their lives according to health issues. Waste management and restaurant sanitation affect everybody.”He said his parents’ public service inspired him to give back to the town.In the next three years – board members serve three-year terms – the Board of Health will oversee the construction of a new transfer station.