What are common themes in The Lovely Bones and The Memory Keeper's Daughter?

What a
great question!  In first looking at the two novels, there might not seem to be many common
themes, but there are.  In fact, there are at least two: the theme of secrecy and the theme of
childhood .

Let's take the theme of secrecy first.  In ,
Susie Salmon is raped and murdered in the early seventies.  It is, of course, the character of
George Harvey who has the issue with secrecy.  Being a serial killer who lures Susie into his
makeshift abode in the middle of a field before raping and killing her, he must keep his
actions, his place of operation, and in fact his life a secret.  Here is how the secret ends up
affecting George Harvey:

A moment later, the icicle fell.
They heavy coldness of it threw him off balance just enough for him to stumble and pitch
forward. It would be weeks before the snow in the ravine melted enough to uncover him.

He lives as "a neighbor" to everyone in Susie's
neighborhood and seems to be a very innocuous person, but lives with a big secret.  In
The Memory Keeper's Daughter, the theme of secrecy is based around the life
of Dr. David Henry.  When his wife, Nora, has twins (which was unexpected) and one of the twins
has the tell-tale signs of Down syndrome, David THINKS he gives the daughter away to an
institution.  (The truth is that Caroline, a nurse at the hospital, raises Phoebe on her own.) 
David then tells the family that the baby girl twin has died.  This secret tears their family
apart.

Now let's approach the theme of tragedy from a parental point of
view.  In The Lovely Bones, Susie Salmon is murdered and the family goes
through all of the typical emotions of horror, grief, anger, acceptance, etc.  Susie's death
doesn't tear the family apart, but affects the family to no end.  In The Memory
Keeper's Daughter, the theme of parental tragedy is based on the supposed death of
the girl twin (which isn't reality) and the secret that David keeps from the family.  Nora goes
through all the grief and anger about her daughter's "death," but then finds her
husband has locked himself into an emotional prison. Why?  Not only because of the guilt of the
secret, but also because of this fact that Caroline is finally able to tell him:

You missed a lot of heartache, sure. But David, you missed a lot of
joy.

Meanwhile, David loses himself with his music. 
David's secret absolutely destroys the family.