David Dearlove, 71, is alleged to have murdered 19-month-old Paul Booth by swinging him by his ankles and smashing his skull against a fireplace.
Dearlove says he found the youngster lying on a concrete floor after falling from his bed.
But the pensioner told a jury yesterday how he would shake him as part of a bedtime play ritual.
Teesside Crown Court heard that Dearlove, when interviewed by police in October 1968, immediately after Paul’s death, told them he had shaken the tot.
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It was something I did all the time. He liked it
In his statement, read by defence barrister Tim Roberts, QC, he said: “I gave him a shaking and he hit his head on the pillow but I don’t think that would have hurt him.”
Asked to explain what he meant, Dearlove said: “It was something I did all the time.
“He liked it.
“I would hold him under the arms.”
Paul’s elder brother Peter, who was then three, claims he witnessed his brother’s fatal injury in Stockton-on-Tees.
He also claims that Dearlove was violent to him and their sister Stephanie.
Richard Wright, prosecuting, asked Dearlove: “Did you love them?” Dearlove replied, “I would say no.”
But when asked, “Did you like them?” Dearlove said yes.
Dearlove, of Great Yarmouth, Norfolk, posted a photograph of himself and Paul on Facebook in 2015.
This provoked fury among relatives, who contacted police.
Dearlove denies murder and manslaughter, plus physical assaults on Peter Booth and Stephanie Marron.
The trial continues.