A man, unhappy with his wife for not giving him a son, burnt her and three daughters, including an infant, alive on Sunday in West Bengal's Murshidabad district, police said.The horrific incident happened in Kandi in the district, about 200 km from here. The attacker has been arrested, police said."We have arrested Ustak Ali (30) for allegedly burning his wife and three daughters alive. The charred bodies of his wife Najifa and three daughters aged 5, 3 and 1 year, were recovered from the house," Superintendent of Police C. Sudhakar said.Sudhakar refused to comment about the motive behind the gruesome killings, but locals alleged that Ali used to repeatedly beat his wife for giving birth to daughters.