Paddy and his pregnant wife live on a farm in the distant rural regions of Ireland.  No running water, no electricity, etc. One night, Paddy's wife is begins to deliver the baby.  The local doctor is there in attendance. "What d'ya want me to do, Doctor?" "Hold the lantern, Paddy, me boy. Here it comes!" the doctor delivers the child and holds it up for the proud father to see. 
"Paddy, you're the proud father of a fine strapping boy." "Saints be praised, I..."
Before Paddy can finish the Doctor interrupts, "Wait a minute. Hold the lantern, Paddy."
Soon the doctor delivers the next  child. "You've a full set now, Paddy. A beautiful baby daughter!" 
"Thanks be to..." Paddy starts to say.
Again the Doctor cuts in, "Hold the lantern, Paddy, Hold the lantern!"
Soon the Doctor delivers a third child.  The doctor holds up the baby for Mike's inspection. "Doctor," asks Paddy, "Do you  think it's the light that's attracting them?"